pictogramme de diamant

Our gemmologists are available to appraise your diamonds

Diamant-Gems has been in the business for over 20 years and is staffed by expert gemmologists trained at the best laboratories in the world, including GIA, HRD and IGI. The gemmology diplomas delivered by these laboratories are recognised worldwide.

Our gemmologists’ role within the company is to establish the origin and quality of the stones in order to determine their market value; this is known as appraisal. Should you need an appraisal for purposes such as an inheritance or upon request by an insurance company, we can provide you with a Replacement Value , document that stipulates all the essential characteristics pertaining to your diamond, as well as its value at the current market price. A fee of €50 (including taxes) will be requested for this service.

We welcome customers by appointment only in our Paris and Antwerp offices. Feel free to contact us any time !


Paris Office
01 47 42 56 56
Antwerp Office
+32 (0)3 226 10 26


There are any number of questions you may have that would lead you to request an appraisal for your jewellery or diamond :

  • Has my diamond been artificially treated? (The wide array of treatments that have been used over the past two decades has made valuing diamonds an even more complex task…).
  • Is my stone a real diamond ?
  • Did the supplier who sold me my diamond actually deliver me one that does not match the certificate ?
  • Is the documentation that was provided with my stone accurate ?
  • Is my diamond damaged or flawed ?
  • Is the documentation provided with my stone a genuine certificate or an altered one ?
  • Does my diamond match its certificate ?
  • Simple curiosity ?
  • You may want to understand the value of an object for inheritance, insurance or divorce purposes ?


The value indicated in the appraisal may differ depending on its nature :

  • Replacement value : Most appraisals are for insurance purposes in order to determine the retail price of a diamond or piece of jewellery in the event of theft. The risks are linked to either burglary or robberies outside of the home (in the street, in public transport…). It is strongly advised to ask your insurance company for an extended warranty for external risks. This is called « insurance on the person », and your insurance company will request a « replacement value ».
  • Market value : we can also perform an appraisal to indicate the price at which the diamond may be purchased or sold on the wholesalers’ secondary market.

Our rate for a written appraisal is the same regardless of your diamond’s carat weight or characteristics : 50 euros, including taxes. Appraisals of diamonds and jewellery items are performed in your presence, by appointment. We may be interested in buying diamonds if they are over 0.50 carats and if their quality is deemed satisfactory. Feel free to contact us for anappraisal on your diamond in Paris or Antwerp.


Below you will find the steps that gemmologists follow and the tools they use when appraising a diamond :


Appraising a diamond

A gemmologist starts an appraisal by cleaning the diamond or piece of jewellery with alcohol. Then they use a small cloth to wipe off any dirt on the surface. For the remainder of the inspection, pliers are used so as not to soil the stone and to make handling easier, especially for smaller stones.

They then observe the diamond using a magnifying glass to assess its impurities. These are specific to each stone and determine its value. Some can be seen with the naked eye, others only using a magnifying glass or microscope. A diamond with inclusions that aren’t visible to the naked eye or with a magnifying glass will be worth more than a diamond whose inclusions can be seen without using special equipment.

Moreover, if the diamond has a laser engraving, the gemmologist will be able to check the number by using a special magnifying glass (that magnifies 20 times rather than 10 times).


instruments diamond appraisal (pliers, magnifying glass, leveridge, cloth)


After the inspection for impurities, the gemmologist determines the colour of the stone using a “daylight” lamp and white cardboard. “Standard” stones are sometimes used if the colour of the diamond is not obvious.

The lamp used to determine the colour of coloured gemstones such as sapphires, rubies and emeralds is different however: the tone is not the same as for “daylight”.

The gemmologist will then weigh the stone using extremely precise scales, the weight being measured in carats. If the diamond is set in a piece of jewellery, a “Leveridge” will be used. This tool measures the dimensions of the diamond in millimetres enabling the gemmologist to estimate the weight.

Once the size, weight, colour and clarity of the stone have been determined, the gemmologist will then test the fluorescence using a UV lamp. Fluorescence in a diamond occurs due to a gas present in the stone and will reduce its market value if present in a high quantity.

Once the appraisal is completed, the gemmologist will establish the market value of the stone. To do so, they will draw on the Rapaport, diamond report, a document that is used for pricing diamonds in real time. Prices are in USD dollars.


Authentication and certification of gems

Gemmologists perform a genuine identification procedure for precious stones that jewellers are rarely able to perform. In the same way, for highly pure diamonds or if you would like us to sell your diamond on the market, we recommend obtaining a certificate from a laboratory such as GIA, HRD or IGI that are all world-renowned and are equipped with the latest technology for detecting possible treatments that a diamond may have been subject to. The certificate is the stone’s identity card and helps ensure its long-term market value.

While diamonds are relatively easy to appraise (weight, size, colour, inclusion) especially in the presence of GIA, HRD or IGI certificate, coloured gemstones, on the other hand, require a different kind of analysis as the value of rubies, sapphires and emeralds depends largely on their colour and their origin. Laboratories that are recognised for examining coloured gemstones are IGI, CARAT GEM LAB, GRS, GÜBELIN.

Do not hesitate to come and have your stones and stone-set jewellery appraised in the Diamant-Gems offices in Paris and Antwerp. Together, we will establish the characteristics in order to determine the value of your possessions.


scales and ultra-violet lamp