Diamonds and Gemstones are born in the depth of the earth. We know the story of their birth as our expert miners are present during the process of excavation. Only Geological Institute of India can tell the origin story of their diamond and gemstone with authenticity. Diamond and Gemstones are God’s gift to us and we are the most trusted source in bringing the gift of diamonds and gemstone to you.
Our story of trust and commitment is inspired by our passion and interest in gemmology science.
We are expert miners who have the knack of digging out the best quality of diamonds and gemstones from the earth and placing them in templates of jewellery. Our mission is to produce genuine and pure gemstones and diamonds at competitive prices to our customers. We are proud to be a reputed mine-marketer, trusted gemmologist and reputed jeweller involved in the complete cycle from birth of a stone till the time it is set in a piece of jewellery.
The best advantage of dealing with us is that there are no middlemen or brokers or agents – only we and our customers. And this is how it is going to be for a life-long lasting customer relationship and tradition of loyalty.
CHARACTERISTICS AND CLASSIFICATION OF GEMSTONE –
It was from the Greeks that we learned the art of classifying our precious and semi-precious rocks. The Western world had classified diamond, ruby, sapphire and emerald, in the bucket of PRECIOUS stones and rest all the other precious and other types of stones into semi-precious. The underlying features of this classification was the quality, rarity and the purest form of the rocks – except for the colourless diamond with hardness of 8 to 10 on the Mohs scale.
Other stones in the semi-precious category are classified on colour, translucency and hardness scale.
In modern times, Gemmologists classify gemstones on their characteristics using technical terminology. The first characteristic a gemmologist uses to identify a gemstone is its chemical composition.
- Diamonds are made of carbon (C) and rubies of aluminium oxide (Al3).
- Many gems fall in the category of crystals which are classified by their crystal system such as cubic or trigonal or monoclinic.
- Ruby is the red variety of the species corundum, while any other color of corundum is considered sapphire.
- Emerald (green), aquamarine (blue), red beryl (red), goshenite (colorless), heliodor (yellow) and morganite (pink), which are all varieties of the mineral species beryl.
Gemstone are also characterized in terms of refractive index, dispersion, specific gravity, hardness, cleavage, fracture and luster. They may exhibit luminescence and a distinctive absorption spectrum. There can be inclusions or darkspots present in other these stones that can be a parameter for classification.
Gemstones may also be classified in terms of their “water”. This is a recognized grading of the gem’s luster, or transparency. We can classify the transparent on basis of transparency scale – high to less.
- First water
- Second water
- Third water
GRADING SYSTEM OF GEMSTONE –
The 10x magnification is universally accepted and developed as the standard grading system of Diamonds by the Gemmological Institute of America (GIA). However, there is no grading system for gemstones. Historically, all gemstones were graded using the naked eye (20/20 vision) and on the skill of the gemmologist.
To understand the factors for grading a diamond the “FOUR C’s”, system was introduced and by adding some modification these categories can be useful in understanding the grading of all gemstones.
The significance of four C’s criteria carry different weight depending upon whether they are applied to gemstones or to diamonds. In gemstone, colour is the primary determinant of quality.
Physical characteristics that make a coloured stone valuable are colour, clarity to a lesser extent, cut, and
Asteria – An asterism is an optical phenomenon displayed by some rubies, sapphires, and other gems of an enhanced reflective area in the shape of a “star” on the surface of a cabochon cut from the stone.
Ancient Greeks loved and greatly valued asteria gemstones as powerful love charms, talisman and offering to gods. There was a belief in the Greek world that asteria gemstones have blessings from the heavens and there is some magic power in these star-conrundum. Helen of Troy was known to have worn star-corundum.
Every laboratory around the world has its own methodology to evaluate gemstones. The procedure of grading can vary but the end-results of revaluation are same. One lab can grade a gemstone are pink in color or another lab can call it rare and beautiful stone of padparadscha color (color of a lotus). Few gemmologists while grading can consider a treatment done on the stone as untreated and other can conclude it is heat-treated.
To minimize such difference of opinion that can create confusion and chaos in the gemstone market, the most leading laboratory in the world have come together have established the Laboratory Manual Harmonisation Committee (LMHC), for the standardization of wording reports, promotion of certain analytical methods and interpretation of results.
We, at Geological Institute of India, are aware of the differences between gem laboratories and will make use of the advanced grading system accepted world-wide to obtain the best possible certificate.
VALUE OF A GEMSTONE –
Gemstones are used in even the most expensive jewellery, décor, exquisite artwork and even used for healing, well-being and other health benefits.
Gemstone pricing and value are governed by factors and characteristics that determine the quality of the stone. The pricing on coloured stones is determined by even by the market supply-and-demand, and also based on the proponents of energy medicine.
CUTTING AND POLISHING OF THE GEMSTONE –
Gemstones are used in different form to be mounted on jewellery pieces or engraved in various art works. Cuts and polishing are done to the gemstones prior to their use.
Stones which are opaque or semi-opaque such as opal, turquoise, etc. are commonly cut as cabochons and are designed to show the stone’s color or surface properties as in opal and star sapphires.
Grinding wheels and polishing agents are used to grind, shape and polish the smooth dome shape of the stones.
Faceted stones – Gems which are transparent are normally faceted, a method that shows the optical properties of the stone’s interior by maximizing reflected light which is perceived as sparkle.
COLORS OF THE GEMSTONE –
When light strikes a material or object, most of the light is absorbed while a smaller amount of a particular frequency or wavelength is reflected. The part that is reflected reaches the eye as the perceived colour. A ruby appears red because it absorbs all the other colours of white light, while reflecting the red.
In Gemstones, sometimes, even the stones with same primary compositon can exhibit different colors. Ruby and sapphire have the same primary chemical composition (both are corundum) but exhibit different colors like red, light red, pink, yellow, dark yellow, white because of impurities.
Although the different stones formally have the same chemical composition and structure, there is a difference in the atomic structure. The difference in the colours and hue in gemstones is due to this atomic heterogeneity. Every now and then an atom is replaced by a completely different atom, sometimes as few as one in a million atoms. These so-called impurities or constantly evolving atomic structure are sufficient to absorb certain colours and leave the other colours unaffected.
Beryl, which is colourless in its pure mineral form, becomes emerald when added with chromium impurities. If manganese is added instead of chromium, then the beryl becomes pink morganite. With iron, it becomes aquamarine and so on.
Due to the modern technology and scientific treatments, some gemmologists make use of these impurities to “manipulate”, the original stone and creating a new gemstone by changing the colour of the gem. Hence, it is important to grade the gemstone and get the Certificate of Grading.
TREATMENT OF THE GEMSTONE –
Gemstones are treated to enhance the color or cut or asteria of the stone but due to the type and extent of treatment, it can affect the value of the stone. Some treatments are used widely are listed below for your information.
Heat – The heating process has been well known to gem miners and cutters for centuries, and heating is a common practice used to treat most of the gemstone to either improve or spoil the colour or clarity of the gemstone.
- Citrine is made by heating amethyst gemstone and with partial heating it becomes an ametrine – partly amethyst and partly Citrine.
- Aquamarine is often heated to remove yellow tones, or to enhance its existing blue colour to a purple.
- Tanzanite is heated at low temperatures to remove brown undertones and make it of a more desirable blue colour.
- Sapphires and rubies are treated with a variety of heat treatments to improve both colour and clarity.
Also, the heating process is not carried out on all gemstone due to the effect of heat on its chemical composition.
- When diamonds are heated it should be protected with boric acid; otherwise the diamond which is pure carbon could be burned completely up.
- When jewellery containing sapphires or rubies are heated, then stones should not be coated with boric acid to avoid any blemishes.
Radiation – Gemstones are been exposed to the process of radiation / irradiation to change or enhance its optical properties or the basic crystal structure. In the process the gemstone is kept in an oven type arrangement like a nuclear reactor and it is heated till the modification process is complete.
Sometimes, the gemstone is exposed to high levels of ionizing radiation to change the atomic structure of the gemstone’s crystal lattice.
Waxing / Oiling – The main purpose of this treatment is to diminish the visibly of fractures by filling these fractures with a substance with wax or oiling them to make these tiny cavities transparent. Gemstones like emeralds contain natural fissures and are filled with wax or oil to disguise them. This process is not like heating or radiation whereby the natural properties of the stone are tempered. Waxing and oiling is a process with enhance the color and clarity of the stone improving its grading quality.
Fracture or Lead Glass Filling –
This process is followed for other precious and semi-precious stones by simply filling these fractures with a substance with similar optical properties makes these tiny cavities transparent.
Diamonds, rubies, and sapphires can be filled with lead glass to improve their clarity. Some gems that combine natural with synthetic material may also be called “hybrid gems.”
SYNTHETIC AND ARTIFICAL GEMSTONES –
Synthetic gemstones are created in a laboratory with the same physical, chemical and optical properties as natural gemstone. Synthetic gemstone or cultured gemstone have the same hardness and density and strength, and show the same colour spectrum, refractive index, and birefringence like natural gemstone and are not imitation or simulated gems. Cubic zirconia is a simulated tone which looks like a diamond but does not possess any chemical or physical characteristics like a diamond.
Synthetic stones have a more vivid color, since impurities are common in natural stones but not present in a synthetic stone.
On the other hand, synthetics stone have more flaws than seen in natural stones, due to corroded metals present in the lab trays used during synthesis.
The gemmological market is full of controversial and differences due to no standard operating process and uniformity of norms. Some of the gemmologists argue that there’s no need to disclose treatments that are indistinguishable from natural gem formation processes to avoid confusing the customers. Others in the industry feel the public’s right to know the outweighs before buying.
However, the Geological Institute of India, operates on 100% transparency guidelines, and disclose the true and accurate information about gemstones to the customer. Our expert panels serving on the gemmological lab front provide the following services to customers before buying from us.
GII Laboratory offers the following services: –
- Identification of the type of gemstones – species and varieties
- Origin certification of Ruby, Emerald and Sapphire (precious stones)
- Identification of natural v/s synthetic vs stimulants of gemstones.
- Identification of treatment / enhanced treatments done on gemstones.