The introduction of 10x magnification as the standard for grading clarity. The inclusions on high quality type 1 colored gemstones are so tiny that they can only be detected under a 10x magnification.
Of course other factors can impact a gem s appearance and structure most notably the cut.
Gemstone grading. Gemstones have no universally accepted grading system. An evaluation of a gemstone s symmetry proportion and appeal while viewing the stone with its table facing the viewer. Black and white are tones from darkest to lightest.
A member of the singapore jewellers association we specialize in diamond grading gemstone identification and jadeite jade identification. Hue and color saturation. A gemstone s clarity grade indicates the relative absence of inclusions materials trapped inside the gem fractures and blemishes surface imperfections that affect its appearance and structural integrity.
Diamonds are graded by whom using a system developed by the gemological institute of america gia in the early 1950s. Light green to greenish blue included weak to low color change. Green to greenish blue slightly included moderate to medium color change.
Gia is the world s most trusted name in diamond grading and gem identification. The basic hues are red orange yellow green blue violet and purple. Type 1 gemstones are usually found almost completely inclusion free within the market.
Deeper green to bluish green clean bright to high color change. With our experienced gemologists we offer you services with integrity reliability and consistency and enjoyable experience learning all about gemstones. However the grading is not limited only to these qualities and other factors such as value for money popularity and even feedback from customers are taken into account while grading gemstones.
An assessment of a gemstone s proportion balance and uniformity determined by a number of criteria including length to width ratio bilateral mirror images etc. Grading the quality of gemstones. Alpha grading is a commonly heard term in conjunction to grading of gemstones this grading is based on several qualities such as colour cut and clarity.
It is recommended that when purchasing a type 1 colored gemstone the buyer should expect the gem to be almost loupe clean. A gem s saturation refers to the intensity of its hue. Gem varieties for grading type 1.
Clarity is one of the four cs of gemstone grading. Black white and brown refer to tones and saturation not hues. Description industry standards agta codes.
With objectivity and expertise as its hallmarks gia ensures the integrity and accuracy of every report it issues. The gia system included a major innovation. We are an independent gem testing and jewellery appraisal laboratory in singapore.
There are other factors taken into consideration when grading colored gemstones such as the quality and rarity of the material enhancements overall size of the stone uniformity of shape quality of cutting faceting and the combination of graded features. Historically all gemstones were graded using the naked eye. Gia tests every material submitted to determine whether it is natural or not and discloses any treatments discovered during our examination.
A gem s tone refers to a gem s relative lightness or darkness.
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