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GUILD Gem Laboratory

GUILDLaboratories

Precision testing, trusted certification, and unwavering commitment to scientific integrity since 1980.

Report Verification
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Frequently Asked Questions

Standard testing typically takes 5–7 business days from the date of reception. Express services are available for urgent requests, with turnaround as short as 1–2 business days, subject to availability.

You can verify any GUILD report by entering the certificate number in the verification tool on this page. Our system will confirm the report's authenticity and display key details from the original certification.

No. GUILD is an independent laboratory that does not engage in any gemstone trading, brokerage, or commercial activities. This strict separation ensures complete objectivity in our testing and certification.

Yes. GUILD reports are widely recognized and accepted by the international gemological community, auction houses, insurance companies, and discerning collectors worldwide.

Terms & Conditions

These Terms and Conditions stipulate the rights and obligations between GUILD Gem Laboratories and clients requesting identification and grading of gemstones.

GUILD provides identification and grading on species and variety, treatment, origin of gemstones, pearl type, environment, and mollusk of pearls in forms of identification certificate, gemology report, grading report, and verbal opinion (hereinafter, the Services). GUILD will only provide testing requested by the client.

Neither the client nor any purchaser of the article(s) shall deem such gem certificate, gemology report, and verbal opinion as a guarantee, valuation, or appraisal for tested items, and GUILD has no representation or warranty regarding the Services described herein.

In the event of any claim by the client or any person for damage to the tested items, or damages resulting directly or indirectly from the Services, the liabilities of GUILD shall in no event exceed two (2) times the amount it receives from the client.

This report contains a record of the physical data of the tested item, including the nature of such item, identity, treatments, and alterations made to the item, as applicable.

All GUILD reports and certificates are printed on the original paper. No correction or alteration of any form shall be accepted on the reports or certificates. A GUILD report or certificate contains the identification of gemstones by photographic image(s), descriptions, measurements, weight, tested data, and states an opinion on their identity, treatment, quality, and rarity, when applicable.

This report or certificate contains only the characteristics and conditions of the item described herein after grading, testing, examination, and analysis using the techniques and equipment available to GUILD at the time of examination. Determination of identity and other data is based on the chemical and physical properties and internal characteristics, using magnification, standardized viewing environment and light source(s), standard and (or) advanced gemological instruments as deemed necessary.

All gem identification and testing are conducted by experienced GUILD gemologists on an independent basis. Opinions may vary in terms of characteristics covered in this report, and results of the examination may differ upon (i) when, how, and by whom the item is examined (ii) changes and improvements in technology and equipment that enable the lab to detect, among other things, treatments previously undetectable, or alterations which become reversible, even if the process remains undetectable.

Neither GUILD nor any of its staff shall, at any time, be held responsible for any discrepancy which may result from the application of new technology or methods.

The client acknowledges and agrees:

  • Not all origins of gemstones are detectable.
  • Gemstones can be treated, retreated, altered, or otherwise processed after identification or testing by GUILD.
  • Advancement of technology may cause or result in a tested item being undetectable of its treatment and (or) synthetic nature at the time of testing when no recognized testing method is publicly available.

The client agrees not to hold GUILD and its employees liable for any loss or damage, special, incidental, or consequential, etc. arising from any omission or description in an identification report or a grading report resulting from human error, defective instruments, delay, or other defects in connection with the testing procedures, issuance or use of the identification report or the grading report unless there is fraud or willful misconduct by GUILD or its agents or employees.

If a client fails to disclose all facts that are known by the client concerning the tested item for which the client requested identification and grading, GUILD and its employees shall be exempted from any and all loss, damage, or expense, etc. incurred as a result of identification and grading.

Conclusion on the identity and treatments of gemstones is an opinion of the laboratory based on the direct comparison of the findings with those obtained from the analysis of reference materials, as well as those in published literature obtainable at the time of examination. As many mines worldwide produce gemstones that display similar properties, an opinion on the most probable geographic origin of the examined gemstones cannot always be given. For the pearl report, the mollusk is an expert opinion based on observation and analytical data and cannot always be given. Mounting may limit complete analysis of the pearl(s), so the details and identification result are described insofar as mounting permits.

Unless expressly agreed otherwise, the client agrees not to hold GUILD liable for the loss or damage of the submitted gemstones resulting from risks that may occur during the transportation and delivery process, including robbery and theft, during the examination process, such as alterations of all kinds including removal of fissure filling in the gem material; and while the gemstone is in possession of GUILD, including theft negligence and natural acts of God.

GUILD may, at its own discretion, re-issue certificates within a period of one year from the issuance of the original certificates upon the client's request. GUILD has the right to retain the items which are not collected or if the number of certificates was not paid within a period of 90 days after the article submitted to GUILD. The laboratory may refuse the issuance of a certificate at any time. GUILD and its employees and agents shall not be liable for any loss, damage, or expense resulting from any error in or omission from this certificate or the issuance of or use of this certificate, even if the loss, damage, or expense was caused by or resulted from the negligence or other fault (except fraud, willful misconduct or gross negligence) of GUILD or any of its employees or agents, and in any event GUILD and its employees and agents shall not be liable for special or consequential damages resulting from any error in or omission from this certificate caused by the acts of others, even if advised of the possibility of such damages. All intellectual property rights belonging to GUILD, more particularly the contents of this Report/Certificate, the name, the design, trademarks, service marks, and logos of GUILD shall not be used in whole or in part for any purpose whatsoever, including for purposes of advertising, publicity or promotion. This report may not be referred to as a guarantee, valuation, or appraisal.

GUILD reserves all the right for the final explanation.

Notes

  1. The color of certain gemstone varieties can be altered by heating and/or irradiation. Such treatment is hardly detectable by current instrumentation.
  2. The color of aquamarine can be altered by heating. Such treatment is hardly detectable by current instrumentation.
  3. The color of morganite can be altered by heating or irradiation. Such treatment is hardly detectable by current instrumentation.
  4. The color of demantoid can be altered by heating. Such treatment is hardly detectable by current instrumentation.
  5. The color of rubellite can be altered by irradiation. Such treatment is hardly detectable by current instrumentation.
  6. The color of Paraiba tourmaline can be altered by heating. Such treatment is hardly detectable by current instrumentation.
  7. The color of zircon can be altered by heating and/or irradiation. Such treatment is hardly detectable by current instrumentation.
  8. The color of tanzanite can be altered by heating. Such treatment is hardly detectable by current instrumentation.
  9. The color of freshwater and akoya pearls can be altered by irradiation. Such treatment can hardly be detected by current instrument and analyses.
  10. Cultured pearls produced in freshwater and akoya pearl oyster are routinely processed.
  11. Some cultured pearls are routinely processed, which may include bleaching, pinking, and luster enhancement.