Guides & expertise · Diamantaires OG
Expertise & appraisal of your GIA diamond
Since 1985, our family-owned house has appraised and purchased diamonds and jewelry at 43 rue Beaubourg, Paris 3rd arrondissement. The appraisal is conducted in front of you by a state-certified gemologist: it is free, no appointment necessary, and without obligation.
The Gemological Institute of America (GIA) is the global standard for diamond certification. Each controlled stone receives a unique certificate number, most often laser-inscribed on the girdle, and publicly searchable in the GIA database. A GIA-certified diamond therefore resells better: its characteristics are attested, verifiable, and indisputable.
We purchase your GIA-certified diamonds from 1 carat: the appraisal is free, the offer is firm, and payment is immediate. We also appraise diamonds certified by IGI, HRD, or EGL — as well as stones without certificates.
How it works
The appraisal in three steps
Present your diamond
No appointment needed at 43 rue Beaubourg (Paris 3rd arrondissement), or remotely: photo via WhatsApp, form, or phone — with or without certificate.
Gemological analysis
A state-certified gemologist checks the 4Cs of your stone and verifies its certificate directly in the laboratory's database (GIA, IGI, HRD…).
Firm offer, immediate payment
You receive a firm offer at market price. If another professional has made you a direct offer, we match it and exceed it.
The 4Cs: how your diamond is evaluated
The GIA has defined the global standard for diamond evaluation, applied by highly qualified gemologists. After analysis, the stone is delivered sealed, the certificate number laser-inscribed on the girdle.
Carat Weight
Weight is measured in carats — 1 carat = 0.20 grams — on a high-precision scale. At equal quality, the price per carat increases in steps: our price guides detail values from 0.5 to 5 carats.
Color
For colorless to tinted diamonds, color is graded from D to Z. Colored diamonds, known as "Fancy," follow their own scale based on hue, saturation, and uniformity — see our color guide.
Clarity
Clarity describes the nature, number, and location of inclusions. The scale ranges from flawless diamonds — FL (Flawless), then IF (Internally Flawless) — to I3: VVS1 and VVS2, VS1 and VS2, SI1 and SI2, then I1, I2, and I3, the so-called "piqué" diamonds, noted P1 to P3 in European nomenclature. For a complete laboratory analysis, the stone must be unset and perfectly cleaned. See our VVS clarity guide.
Cut
Cut is evaluated through proportions (ratios between crown, pavilion, total height, and diameter), symmetry, and polish, graded from Excellent to Poor. Dimensions are expressed in millimeters.
The certificate also mentions fluorescence — the stone's reaction to ultraviolet light, graded from None to Very Strong —, indicates any treatments, and attests that the diamond is natural and not synthetic. To understand each section of the report, consult our GIA certificate guide.
Further reading
Certificates, prices, and quality
The GIA certificate decoded
Grading report, proportions, laser inscription: understand each section of your certificate.
Read the guide →
Prices per carat
From 0.5 to 5 carats: current price benchmarks to gauge your diamond's value.
Read the guide →
The 4Cs in detail
Color, clarity, cut, carat: the criteria that determine a diamond's quality — and price.
Read the guide →Free appraisal, no obligation
How much is your diamond worth?
Appraisal by a state-certified gemologist — firm offer, immediate payment.
All our diamond guides
All our guides, written by the house, to understand certification, assess the quality of a stone and determine its price.
Laboratories & certificates
- ◆ The GIA certificate decoded
- ◆ What is the GIA?
- ◆ The IGI laboratory
- ◆ Selling an HRD diamond
- ◆ Expertise of an EGL diamond
- ◆ French gemological laboratories
- ◆ SCAN or CIBJO certified diamonds
- ◆ Getting your diamond certified
Evaluate your diamond
- ◆ The 4Cs of diamond quality
- ◆ Diamond color
- ◆ VVS clarity
- ◆ Diamond shapes
- ◆ Getting the weight of a diamond
Price per carat
- ◆ The complete diamond price guide
- ◆ Price of a 0.5 carat diamond
- ◆ Price of a 1 carat diamond
- ◆ Price of a 1.5 carat diamond
- ◆ Price of a 2 carat diamond
- ◆ Price of a 3 carat diamond
- ◆ Price of a 4 carat diamond
- ◆ Price of a 5 carat diamond
The expertise is carried out by our gemologists, in our offices in the 3rd arrondissement — see our diamond house in Paris.
Frequently asked questions
Diamond expertise in practice
How can I get a free estimate for my GIA certified diamond?+
Call us at 01 48 87 81 44, visit us without an appointment at 43 rue Beaubourg 75003 Paris, or describe your stone via the form on this page: a state-certified gemologist will respond within 24 hours.
What guarantee do you offer on the purchase of a GIA diamond?+
We guarantee the best purchase terms: if you have a direct purchase offer from a competitor, we will match it and commit to offering you a higher price.
What are the criteria for evaluating a diamond by the GIA?+
The GIA evaluates each diamond according to the 4Cs: color, clarity, cut, and carat weight. Each stone receives a unique certificate number, publicly verifiable in the GIA database.
Why does GIA certification add value to a diamond?+
The Gemological Institute of America is the global reference for certification: a diamond that has passed its very demanding controls resells better, because its characteristics are attested and verifiable by everyone.
What are the hours for an in-store expertise?+
Monday to Friday from 10am to 1pm and from 2pm to 6:30pm, at 43 rue Beaubourg 75003 Paris (M° Rambuteau), with or without an appointment.
Do you also sell diamonds and jewelry?+
Yes — our boutique presents certified diamonds and signed jewelry selected by the house, to discover online or at 43 rue Beaubourg.
Can I get a remote pre-expertise before coming in?+
Yes: send a photo via WhatsApp or describe your stone by email ([email protected]) or via the form — you will receive an initial evaluation, then refined in-store, in front of you.
Free expertise
Have your diamond appraised
Describe your stone — with or without a certificate — or simply send a photo via WhatsApp. Your request remains strictly confidential.
- ◆ Response within 24 hours by a state-certified gemologist
- ◆ Free and without obligation
- ◆ Firm offer, immediate payment in-store