Goa Stylish Jewellery.
By Aamir Mannan.
Thus the ray AO is refracted along OA', apart from the small fraction of light which is reflected at O, as indicated by the dotted line. similarly, the ray BO is refracted along OB', as we consider rays which form greater angles with the normal, NOM, we reach an angle where the refracted ray only just grazes along the surface, OQ, between the two media. this angle is know as the critical angle, and all ray reaching O form the denser medium at angle greater than the critical angle are totally reflected back into the denser medium, it being physically
impossible for any light form such rays to penetrate into the rarer medium. in the post, the angle COM can be considered as the critical angle of incidence; all the light s thus totally reflected along OC", and any other rays, such as DO, with a still larger of incidence, is, of course, also totally reflected. it is important to realise that the size of the critical angles will depend upon the
Bihari Bridal Jewellery.
By Aamir Mannan.
Colours plays an extermely important part in contributing to the beauty and popularity of precious stones. it was their colour that made such stones as turquoise and lapis lazuli among the first to attract the cupidity of early civilised man, and it is the mangnificent crimson red of ruby, the deep cornflower blue of the finest sapphires and the verdant green of emerald which (added to their transparency, hardness and rarity) have caused them always to rank amongst the supremely precious gems. only in the case of diamond, unique in this as in so many other ways, has a complete lack of colour been regarded as the standard of perfection. those unversed in gemmology find it hard to realise that is most of the mineral species used as gems a wide colour range is possible, and that in their 'pure' state they would be colourless and thereby of
relatively little value.It has already been stated that each mineral has a definite refractive index by which it can be identified on the refractometer; list of these indices will be found on p. 27, and at the of the post. for the benefit of those who like to have at least a rough idea of the working of an instrument which they are using, a short description of the basic principle upon which all gem-tasting refractometer depend followers. however, those, who would like to know how to use a refractometer, but who prefer to shirk such explanation, can skip the next section and await the strictly practical directions which will be given later, on
Tripura Bridal Wedding Jewellery.
By Aamir Mannan.
Colours plays an extermely important part in contributing to the beauty and popularity of precious stones. it was their colour that made such stones as turquoise and lapis lazuli among the first to attract the cupidity of early civilised man, and it is the mangnificent crimson red of ruby, the deep cornflower blue of the finest sapphires and the verdant green of emerald which (added to their transparency, hardness and rarity) have caused them always to rank amongst the supremely precious gems. only in the case of diamond, unique in this as in so many other ways, has a
complete lack of colour been regarded as the standard of perfection. those unversed in gemmology find it hard to realise that is most of the mineral species used as gems a wide colour range is possible, and that in their 'pure' state they would be colourless and thereby of relatively little value.It has already been stated that each mineral has a definite refractive index by which it can be identified on the refractometer; list of these indices will be found on p. 27, and at the of the post. for the benefit of those who like to have at least a rough idea of the working of an instrument which they are using, a short description of the basic principle upon which
West Bengal Bridal Jewellery.
By Aamir Mannan.
In some minerals the figures very somewhat; thus in zircon, while the blue, white, and golden 'fried' type most popular in moderan jewellery are almost constant in their birefringence of 0.059. many of the ceyclonese
zircons. particularly the green varieties, have a much lower double refractions, sinking in some cases practically to zero. this peculiaity is unique amongst minerals, and will be discussed at greater length in the chapter on zircon. synthetic rutile has been manufactured in the USA (since 1949), and its anormous double refraction will be one means of identification. calcite, though not a gemstone, plays an important part in gemmological instruments in its optocally pure form of 'ice land spar', how, apart from the refractometer, can one test whether a given stone doubly refractive or not? the simplest method of all, which with a little
Indian Kerala Bridal Jewellery.
By Aamir Mannan.
This deviation of rays of light on entering a new medium is called refraction. In figure 2.1 the rays of light, I.O, is refracted along OR on entering the denser medium blow the surface PQ. The broken line show the path of followed by the reflacted light. The extent of the bending of refraction of light on entering the stone depends upon its refracting
power or 'refractive index', and this is inversely proportional to the velocity of light withing the substance. Put differently, the refractive index of a medium may be define as the velocity of light in air* divided by the velocity of light in the medium. The velocity of light in air approximately I86,000 miles per second, and light from the sun and stars travel to us at this immense speed. In quartz (rock, crystal, amethyst, etc) the velocity is reduced to approximately I20,000 and its diamond to only 76,860 miles per second. Thus diamond, in which light travels as mentioned above, at 76,860 miles per second in empty space, has
Andhra Pradesh Bridal Jewellery.
By Aamir Mannan.
9.COLOUR, COLOUR FILTERS, AND THE DICHROSCOPE
It is the presence of traces of these in an otherwise colourless crystal that produces their colour varieties. more will be said about the function of these 'transition' element , when dealing with the spectroscope. granted that there are a considerable number of red, blue and green gemstones, there are very few that can approach ruby, sapphire and emerald in their rich shades of these colour and a colour sensitive and trained eye can go a long
way towards distinguishing them from other natural gemstones, glass imitations, or even synthetic counterparts. it is indeed worthwhile for a beginning gemmologist to practice at every opportunity the sight identifications of the various gems and to pay special attention to the particular grades of colour typical of each species.
Gujarati Bridal Jewellery.
By Aamir Mannan.
8.DOUBLE REFRACTION AND DISPERSION
Thus is must be realised that if, say, a zircon is cut with is table facet at right-angles to optic axis it may be necessary to tile the stone and make observations trough the bezel facets to see the double refraction well developed. also, as R. T. liddicoat has pointed out, in directions at right-angle to the optic axis of the uniaxial minerals, although the double refraction is at is greatest is cannot be directly observed, as the image due to the extraordinary ray is either directly in front or directly behind
that the due to the ordinary ray. with zircon, sphene, and peridot the birefringence is so strong that even the novice should have no difficultly in seeing the effect mentioned effect in quartz and corundum unless the stone are larger. (J.-P. Poirot, director of the paris gem-testing laboratory, has made the important observation that for a given birefringence the doubling effects is more marked in stones of low R.I. than in those of high index.)
Uttar Pradesh Bridal Jewellery.
By Aamir Mannan.
8.DOUBLE REFRACTION AND DISPERSION
Thus is must be realised that if, say, a zircon is cut with is table facet at right-angles to optic axis it may be necessary to tile the stone and make observations trough the bezel facets to see the double refraction well developed. also, as R. T. liddicoat has pointed out, in directions at right-angle to the optic axis of the uniaxial minerals, although the double refraction is at is greatest is cannot be directly observed, as the image due to
the extraordinary ray is either directly in front or directly behind that the due to the ordinary ray. with zircon, sphene, and peridot the birefringence is so strong that even the novice should have no difficultly in seeing the effect mentioned effect in quartz and corundum unless the stone are larger. (J.-P. Poirot, director of the paris gem-testing laboratory, has made the important observation that for a given birefringence the doubling effects is more marked in stones of low R.I. than in those of high index.)
Maharashtrian Bridal Jewellery.
By Aamir Mannan.
7.REFRACTIVE INDEX AND ITS MEASUREMENT
Thus the ray AO is refracted along OA', apart from the small fraction of light which is reflected at O, as indicated by the dotted line. similarly, the ray BO is refracted along OB', as we
consider rays which form greater angles with the normal, NOM, we reach an angle where the refracted ray only just grazes along the surface, OQ, between the two media. this angle is know as the critical angle, and all ray reaching O form the denser medium at angle greater than the critical angle are totally reflected back into the denser medium, it being physically impossible for any light form such rays to
Indian Rakhi Gents Bracelet Jewellery.
6.COLOUR, COLOUR FILTERS, AND THE DICHROSCOPE
By Aamir Mannan.
While ruby and supphire are the red and blue varieties of the mineral corundum, there are also white, yellow, pink and green supphires. emerald and aquamarine are the rich green and pale blue varieties of beryls, but there are also white, pink, and yellow beryls, and green beryl that do not rank as emeralds, tourmaline, quartz, zircon and topaz are further well-known examples of such polychrome minerals, and tourmaline in particular
is well known for frequently appearing as parti-coloured crystals, the boundaries between the colours -(usually green and pink) being quite sharp either across the length of the crystal or concentrically in zones. the reason of such confusing behaviour can usually be explained by the fact that there are a limited number (eight to be precise) of elements that give rise to colour in minerals.
Indian Assam Bridal Wedding Jewellery.
By Aamir Mannan.
4.REFRACTIVE INDEX AND ITS MEASUREMENT
It has already been stated that each mineral has a definite refractive index by which it can be identified on the refractometer; list of these indices will be found on p. 27, and at the of the post. for the benefit of those who like to have at least a rough idea of the working of an instrument which they are using, a short description of the basic principle upon which all gem-tasting refractometer depend followers. however, those, who would like to know how to use a refractometer, but who prefer to shirk such explanation, can skip the next section and await the strictly practical directions which will be given later, on
Jammu and Kashmir Bridal Jewellery.
By Aamir Mannan.
5..DOUBLE REFRACTION AND DISPERSION
As would appear in a singly refractive stone such as diamond, each edge appears as a double line (see figure 3.1). a word of warning, however, should be uttered here; according to their crystal structure, all doubly refracting stones have either one or two direction in which only single refraction obtains. those gemstones belonging to the tetragonal, trigonal or hexagonal system
of crystals have only such direction; one 'optic axis' as it called. these minerals, which are grouped together optically us 'uniaxal', include zircon, corundum (ruby and sapphire), beryl (emerald and aquamarine), tourmaline, and quartz (amethyst and citrine). the minerals crystallising in either the orthorhombic, monoclinic or triclinic systems have two optic axes, and are called 'biaxial'. these include peridot, chrysoberal (alexandrite), topaz, and spodumene (kunzite) among the coommoner gemstones.
Indian Karnataka Bridal Jewellery.
By Aamir Mannan.
4.REFRACTIVE INDEX AND ITS MEASUREMENT
It has already been stated that each mineral has a definite refractive index by which it can be identified on the refractometer; list of these indices will be found on p. 27, and at the of the post. for the benefit of those who like to have at least a rough idea of the working of an instrument which they are using, a short description of the basic principle upon which all gem-tasting refractometer depend followers. however, those, who would like to know how to use a refractometer, but who prefer to shirk such explanation, can skip the next section
Indian Bridal Wedding Jewellery
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Insurance of Jewelry Basic Need
Should the unforeseeable occur and you suffer a loss, Warren Jewelers works closely with your insurance company to help you with replacement or compensation of your valuable jewelry or family heirloom.
Things you need to know about Jewelry Insurance:
Insurance Regulations
State laws differ but are regulated by the Insurance Commissioner and insurance departments of the individual states. Some states tightly regulate insurance company contract language and other states allow insurance companies to write contracts with their own language. You should discuss your insurance needs with your insurance agent. If you do suffer a loss you do have the right to choose the jeweler who you trust to replace the item. Your insurance company may make suggestions but it is up to you to tell your insurance companying whom you would like to use to replace the item.
Insurance Coverage
Most jewelry is covered under your homeowners or renters insurance policy. You can also buy private jewelry insurance.
Basic Insurance
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Unscheduled personal property includes jewelry which would be covered by your homeowners or renters insurance. However, in most policies not all losses are covered. In addition there are low dollar limits on unscheduled personal property. In a case of a large theft you may only be covered for a total loss as low as $500.00 compensation. For any item of jewelry with a value over $1000.00 you should schedule your jewelry to cover specific items. This is done with a Personal Articles Floater, which is attached to a homeowner or renters policy. You can also purchase a stand-alone or private jewelry insurance policy. The coverage on these types of insurance can be very broad covering all types of losses with very few exclusions.
Premiums or Cost to Insure
Fashion Abhayapuri Jewellery.
By Aamir Mannan.
3.COLOUR, COLOUR FILTERS, AND THE DICHROSCOPE
Colours plays an extermely important part in contributing to the beauty and popularity of precious stones. it was their colour that made such stones as turquoise and lapis lazuli among the first to attract the cupidity of early civilised man, and it is the mangnificent crimson red of ruby, the deep cornflower blue of the finest sapphires and the verdant green of emerald which (added to their transparency, hardness and rarity) have caused them always to rank amongst the supremely precious gems. only in the case of
Indian Gujarati Jewellery.
By Aamir Mannan.
2.DOUBLE REFRACTION AND DISPERSION
In some minerals the figures very somewhat; thus in zircon, while the blue, white, and golden 'fried' type most popular in moderan jewellery are almost constant in their birefringence of 0.059. many of the ceyclonese
zircons. particularly the green varieties, have a much lower double refractions, sinking in some cases practically to zero. this peculiaity is unique amongst minerals, and will be discussed at greater length in the chapter on zircon. synthetic rutile has been manufactured in the USA (since 1949), and its anormous double refraction will be one means of identification. calcite, though not a gemstone, plays an important
Indian Kundan Bridal Jewellery
By Aamir Mannan.
1.REFRACTIVE INDEX AND ITS MEASUREMENT
This deviation of rays of light on entering a new medium is called refraction. In figure 2.1 the rays of light, I.O, is refracted along OR on entering the denser medium blow the surface PQ. The broken line show the path of followed by the reflacted light. The extent of the bending of refraction of light on entering the stone depends upon its refracting power or 'refractive index', and this is inversely
proportional to the velocity of light withing the substance. Put differently, the refractive index of a medium may be define as the velocity of light in air* divided by the velocity of light in the medium. The velocity of light in air approximately I86,000 miles per second, and light from the sun and stars travel to us at this immense speed. In quartz (rock, crystal, amethyst, etc) the velocity is reduced to approximately I20,000 and its diamond to only 76,860 miles per second. Thus diamond, in
Indian Hyderabad Bridal Jewellery.
By Aamir Mannan.
REFRACTIVE INDEX AND ITS MEASUREMENT
The first task identifying a gemstones is to make quite sure to what mineral species it belongs: to determine, for instance, whether it is a corundum (ruby or supphire), a beryl (emerald or aquamarine), quartz (amethyst or citrine), topaz, tourmaline, spinal, peridot, or zircon.Though one may often make a shrewd guess as to the nature of a stone by reason of its colour, lustre, and general appearance, it is often only by measuring one or other of its optical or physicals 'constants' that one can be really sure of once's ground.In this chapter methods are described for measuring the most important of these constant.Men is a profoundly lazy creature and its has been said that most of his inventions has been born of the urge to save himself trouble.Presumably, therefor, jewellers who are not scientifically minded would welcome an apparatus which would enable stones to be identified in some really simple manners, quickly, clearly, and without calculations.If, merely by placing the
table facet of an unknown stones on an instrument, its name could be read off by mean of a pointer on a calibrated scale, one would expect such an apparatus to be widely popular.Instrument closely corresponding to this 'ideal' have in fact been designed and marketed (at rather a high price) during recent years.These reflectivity meters aim to identify gemstones, where these have a clean and well polished table facet, by measured their reflecting power when a narrow bean of infra-red light impinges on this facet.Such instruments have certain distinct advantages over the traditions types of jeweller's refractometer that have been the mainstay
Indian Beautiful Bridal Jewelley.
By Aamir Mannan.
These reflectivity meters aim to identify gemstones, where these have a clean and well polished table facet, by measured their reflecting power when a narrow bean of infra-red light impinges on this facet.
Such instruments have certain distinct advantages over the traditions types of jeweller's refractometer that have been the mainstay of gems identifications for three-quarters of a century.
But they also have grave limitations, which are explained later in this chapter.
The refractometer in still an essential instrument for the gemmologist, and the principles of its constructions and hoe to make the best use of it are fully explained later.
First, however we must explain the meaning of refraction and refractive index and the basic principles on which the refractometer operates.
What happens when a ray of light fall on the surface of a transparent solid such as a gemstones or a sheet of glass? Some of the light is reflected at the surface of the stone.
The reflected light leaving the surface at an angle equal to that at which it falls upon the surface ('incident angle' or 'angle of incident').
Indian Jewellery.
By AamirMannan.
These reflectivity meters aim to identify gemstones, where these have a clean and well polished table facet, by measured their reflecting power when a narrow bean of infra-red light impinges on this facet.
Such instruments have certain distinct advantages over the traditions types of jeweller's refractometer that have been the mainstay of gems identifications for three-quarters of a century.
But they also have grave limitations, which are explained later in this chapter.
The refractometer in still an essential instrument for the gemmologist, and the principles of its constructions and hoe to make the best use of it are fully explained later.
First, however we must explain the meaning of refraction and refractive index and the basic principles on which the refractometer operates.
What happens when a ray of light fall on the surface of a transparent solid such as a gemstones or a sheet of glass? Some of the light is reflected at the surface of the stone.
The reflected light leaving the surface at an angle equal to that at which it falls upon the surface ('incident angle' or 'angle of incident').
Insurance of Jewelry Basic Need.
By Aamir Mannan.
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Should the unforeseeable occur and you suffer a loss, Warren Jewelers works closely with your insurance company to help you with replacement or compensation of your valuable jewelry or family heirloom.
Things you need to know about Jewelry Insurance:
Insurance Regulations
State laws differ but are regulated by the Insurance Commissioner and insurance departments of the individual states. Some states tightly regulate insurance company contract language and other states allow insurance companies to write contracts with their own language. You should discuss your insurance needs with your insurance agent. If you do suffer a loss you do have the right to choose the jeweler who you trust to replace the item. Your insurance company may make suggestions but it is up to you to tell your insurance comp anying whom you would like to use to replace the item.
Insurance Coverage
.jpg)
Most jewelry is covered under your homeowners or renters insurance policy. You can also buy private jewelry insurance.
Basic Insurance
Unscheduled personal property includes jewelry which would be covered by your homeowners or renters insurance. However, in most policies not all losses are covered. In addition there are low dollar limits on unscheduled personal property. In a case of a large theft you may only be covered for a total loss as low as $500.00 compensation. For any item of jewelry with a value over $1000.00 you should schedule your jewelry to cover specific items. This is done with a Personal Articles Floater, which is attached to a homeowner or renters policy. You can also purchase a stand-alone or private jewelry insurance policy. The coverage on these types of insurance can be very broad covering all types of losses with very few exclusions.
Premiums or Cost to Insure
Indian Fashion Bridal Jewellery Collection.
By AamirMannan.
REFRACTIVE INDEX AND ITS MEASUREMENT
The first task identifying a gemstones is to make quite sure to what mineral species it belongs: to determine, for instance, whether it is a corundum (ruby or supphire), a beryl (emerald or aquamarine), quartz (amethyst or citrine), topaz, tourmaline, spinal, peridot, or zircon.
Diamond Bridal Necklace Sets.
By Aamir Mannan.
Since this is not an academic treatise but a practical guide for a jeweler-gemmologist, the order in which the individual stone are dealt with is roughly based on their commercial importance.Diamond Quite clearly precedence to over any other, followed by ruby, sapphire and emerald, these four being the classical 'precious stone' in the days when all others (except pearl) were relegated to the ' semiprecious' ranks.Thereafter the order of the chapters becomes less predictable, but if the reader fails to find the stone in which he is interested quickly he has only to consult the index.
Diamond accounts for over 90 per cent by value of the world's trade in gems, and is one of the few stones that every jewelers handles and hopes to be able to recognise at sight when tolerable certainty.
There have been many cases, however, when even experienced dealers have made costly (and humiliating) mistakes-very often because their suspicion have not been aroused.
Indian Wedding Bridal Sapphire Jewellery.
By Aamir Mannan.
THE IDENTIFICATIONS OF SAPPHIRE
As in the case of ruby, the most effective substitute for natural sapphire is it
synthetic counterpart, and the method for detecting the difference between the natural and the manufactured stone will be found bellow, although the whole subject of synthetics has already been dealt with in chapter 7.The cobalt-blue forms of synthetic spinal must also be considered as a sapphire substitute, since this is their raison D'etre.
Glass imitations of sapphire are not often seen, since the synthetics stones are clearly more effective as a substitute.
The old-fashioned garnet-topped doublet on a blue glass base is also seldom seen, but a much more effective type of doublet has been exploited in recent year, in which a crown of natural australian sapphire cemented to a base of synthetic blue sapphire; fuller reference to this type of doublet will be found at the end of this chapter.
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