Analyses and separates diamonds from simulants, laboratory-grown and potentially HPHT treated natural diamonds.
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GIA established the 4Cs (Cut, Clarity, Color, Carat Weight) - the global standards for evaluating diamond quality.
Anyone around the world can submit diamonds and coloured gemstones to GIA and be assured of consistent quality standards, service, and fee structures. Menu of services offered will change with location.
Read the instructions for submitting stones to GIA locations worldwide. Whether you choose to ship your items to us, or drop them off in person, here are a few tips to help ensure the quick return of your items etc.
GIA LabDirect, a system of authorized, third-party consolidators, provides easy, convenient access to GIA Laboratory services from a growing number of locations outside the U.S. With GIA LabDirect, international customers can deliver and pick up their items locally, transact business in their own languages, and get help with packaging, insurance, customs and the many complicated details of shipping valuables internationally. Please contact GIA LabDirect consolidators for their hours of operation, specific payment instructions, and other details.
Please contact us for details.
For the ultimate peace of mind, ask your jeweller to provide an independent diamond grading report with your diamond. The most widely used and respected reports are those issued by independent GIA, which provides grading reports on the world's most important diamonds. A professional jeweller can arrange to have your diamond graded and even have a personal message or unique GIA Diamond Grading Report number laser-inscribed onto the diamond's girdle (its outer edge).
A micro-laser beam can be used to etch a microscopic inscription on the girdle of any diamond weighing 0.25 carat or more. Inscriptions are most often used to give a diamond a unique identification. For example, report numbers or other information relating to ownership are often inscribed. However, romantic messages like 'Forever Yours' and 'Always and Forever' have become popular, along with poetry, symbols, names and special dates. Since a message can be read only under magnification, you and your special someone can keep it to yourselves or choose to share it with others. The price of GIA's inscription service is based on the weight of the diamond and the length of the inscription. Typically, up to 15 character spaces can be inscribed.
A GIA report offers technical information on the dimensions, quality and identifying characteristics of a loose diamond, but does not provide an appraisal value. Later, value may be determined from the information provided by a GIA Diamond Grading Report. If your diamond is mounted and you would like to have an appraisal of the entire piece of jewellery, an independent appraiser can provide this service. An appraisal provides a quality analysis, description and a valuation of a jewellery item.
There are many appraisal associations that can assist you with locating an appraiser.
GIA's high-tech analytical instruments include:
GIA reports are available only in English at this time.
Yes. GIA offers a cut grade for standard round brilliant diamonds in the GIA D-to-Z colour range, assigning one of five grades ranging from excellent to poor. Each cut grade represents a range of proportion sets and diamond appearances, each of which may conform in different ways to the characteristics of that grade. The GIA Cut Grade is reported on the GIA Diamond Grading Report for diamonds 0.15 ct. and larger and on the GIA Diamond Dossier for diamonds 0.15-1.99 ct.
Yes, we grade all polished diamonds regardless of shape or brand. We evaluate all diamonds according to the GIA International Diamond Grading System, which takes into consideration the 4Cs. With fancy or specialty cuts, however, we only evaluate Colour, Clarity, and Carat Weight. We do support the marketing and branding of these cuts with laser inscription and reporting of brand names. Our extensive library of over 500 plotting diagrams includes many branded and specialty cuts. We judge the appearance of these special cuts compared with one another, or with the standard round brilliant.
Over the past several years, we have generally seen improvements in the polishing of diamonds, including the placement and alignment of facets, the exactness in the angular relationships between facets and the quality of polishing. With the introduction of GIA's cut grade for round brilliants in 2005, we have also noticed that efforts are under way to pay closer attention to previously ignored aspects of diamond polishing.
No. Filling of diamond fractures with a glass is not a stable, permanent treatment; grading results would be affected if the filler is damaged or removed.
Do you grade polished laboratory-grown diamonds?
Yes. In June 2006, GIA announced it would begin offering laboratory-grown diamond grading reports to the public and the trade to provide consumers with the necessary information and disclosure. GIA evaluates laboratory-grown diamonds using the same colour and clarity boundaries as the grading system for natural diamonds, but with fewer quality grade categories.
Performance analysis implies that some type of methodology analyse light emitted from a diamond in the same way that the human eye does. GIA's past research found no existing technology capable of such analysis. To compensate for this, GIA used proprietary ray-tracing software to develop a system that would predict brightness and fire from a variety of proportions sets (angles and dimensions) input into the computer. In order to determine which diamonds were perceived as best, GIA showed diamonds with a wide variety of proportions to diamond manufacturers, jewellers and consumers. Observations were conducted in dealer's offices, where jewellers did their buying, and other locations. Other observation tests were conducted in controlled lighting environments. Through this research, GIA determined that the pattern--the size and arrangement of bright and dark areas in a diamon--was essential to the assessment of a diamond's appearance. Formulas were determined that could predict when certain areas of a diamond were dark or bright for the observer. Grade boundaries were based on the threshold at which the combination of brightness, fire and pattern were perceived to be the best; as observers saw detracting differences in appearance, various grade levels were established. Human observation testing was used to set the thresholds for the five grades -- Excellent, Very Good, Good, Fair and Poor. GIA created lookup tables incorporating these factors; they also included weight ratio, girdle thickness, polish, finish and symmetry. When the angles and dimensions of a diamond are measured on a non-contact measuring device, those measurements are used to access the lookup tables and determine a final grade.