Gemstone Certification
A gemstone certificate is issued following an unbiased and professional examination to authenticate a gemstone’s attributes. The carat weight, colour and clarity are all validated, together with the gemstone’s exact measurements. Certificates are essential in determining or testifying a gemstone’s value. Gemstones sold through NexusGems.Com have been graded by GIA, IGI (International or USA). It is generally accepted by loose gemstones industry professionals that the Gemmological Institute of America (GIA) sets the standard when it comes to gemstone’s grading. At least three-quarters of the 1000 gemstones listed on NexusGems.com have been graded by the IGI.
BEWARE: Always buy a certificated Loose Gemstones – Unless you are purchasing smaller gemstones with fewer carats. To be certain of the gemstone quality insist on a certificate – If your gemstone is not certified by internationally recognised certificates listed above, chances are the attributes stated is misleading and that you are purchasing something of lesser quality than indicated. Unfortunately some retail shops and online stores self-certify, for the sole purpose of increasing their margin on the product sold.
Certificate Comparisons:
The most renowned and trusted gemmological grading laboratories are as follows
Gemmological Institute Of America (GIA) :
Analysis and grading:
GIA is the world’s most trusted name in gemstones grading and gemstone identification. With objectivity and expertise as its hallmarks, GIA ensures the integrity and accuracy of every report it issues. GIA tests every material submitted to determine whether it is natural or not, and discloses any known treatments discovered during analysis.
How does gia test colored stones?
For each item submitted, a gemmologist uses a battery of traditional and advanced instruments to perform a variety of analytical investigations, including microscopic examinations, and tests to determine an item’s gemmological identity and detect any treatments. The process is independently repeated by a second gemmologist, and may be further examined by additional gemmologists and researchers as needed.
GIA receives a varied and complex range of items for identification; everything from colored stones and pearls, unusual carvings and jewelry, to the latest in synthetics, and simulants, as well as treated gems. A significant area of activity involves the origin of color in gemstones, most notably, but far from limited to, gemstoness, rubies, and sapphires.
Inspection, care, and handling procedures
GIA applies the same item identification and tracking procedures to gem identification as it does to gemstones grading. Each item is assigned a bar-coded label with a unique internal identification number that is used to track it throughout the process. And at every step, special inspection, care, and handling procedures serve to protect a gem’s identity and ensure it is managed with the utmost care.
Weights and measures
This is the first stop for any gemstone. Loose gems are weighed with an electronic micro-balance that captures the weight to the fifth decimal place. Loose polished stones are also measured with an optical measuring device to determine their proportions, measurements and facet angles. Mounted stones are measured, but not weighed.
Identification
Items are then transferred to the Identification Inventory Control department for distribution to trained and experienced gemmologists for servicing. Once an item is received by an initial gemmologist, its recorded weight and measurements are verified, or if the item is mounted or strung, the gemmologist will use manual measuring devices to determine and record necessary measurements.
Employing state-of-the-art technology in his research and identification efforts, the gemmologist then performs a variety of analytical investigations, including a microscopic examination of the item, and performs all the tests required to properly determine its gemmological identity and detect any treatments.
After that, the item is transferred to a second gemmologist, who independently performs all necessary observations and testing. Depending on the identity and nature of the item, it may be examined by additional gemmologists and research specialists.
Report processing and item return
Reports are generated after all results are finalized and services have been completed. All GIA Reports are examined and proofread to ensure quality before being sent to the client.
Last, the item is placed in its original container, joined with its report, and goes through final inspection and testing to ensure that the same submitted item is returned to the client.
Items are returned either in person through the Client Services department, or via courier through the Transport Services department. All information recorded for an item remains stored in the GIA laboratory’s permanent database for future reference.
International gemological institute (IGI) :
International Gemmological Institute (IGI) is the largest independent laboratory for grading and evaluating gemstones and fine jewellery, and is renowned for its quality services, extensive experience and expertise.
Besides exceptional stones, a gem has no name, no history. It’s a gem! The final user doesn’t know where the stone was found, who extracted it, which polished it or the name of the gem dealer. The only document that travels around the world with the gem is the gemmological report. The IGI report is “The Passport for your gems and jewellery!.
The IGI Gemstones Report is essentially a statement attesting to the authenticity of a gemstones and provides a reliable and accurate report of its identity and grade based on an internationally recognized system. Each gemstones is scientifically analysed by several gemmologists who use their experience in combination with state-of-the-art equipment to produce an accurate description of the characteristics of the gemstones and the quality of its cut. With its detailed information presented in understandable language, the different qualities of a gemstones can be truly appreciated.
The grade or quality of a gemstones is based on four characteristics commonly referred to as the 4Cs: the Carat weight, Colour, Clarity, and Cut. These are analysed and the results are recorded in the IGI Gemstones Report.
Analysis and grading:
IGI laboratories are equipped with the most technologically advanced instruments for the identification and authentication of colored stones. These instruments include immersion cells, micrometers, spectroscopes, polariscopes, refractometers, specific gravity liquids, binocular microscopes and spectrophotometers.
Techniques such as stone coating, diffusion treatment, heat treatment, polymer impregnation and clarity enhancement as well as sophisticated developments in creating synthetic gems, are commonplace today.
IGI’s approach to colored stone analysis is extremely important to you, especially in light of the fast-evolving new techniques being used to alter and treat rubies, sapphires, emeralds and other stones.
Colored stone identification report
The colored stone identification report identifies the gemstone’s specific variety, shape and cut, carat weight, measurements, colour quality and transparency factor, as well as other major optical characteristics. Disclosure of treatments is also noted in this report. Upon request, country of origin may be determined. The certificate clearly states if the stone is natural or synthetic.