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Diamond certificates provide much information, but there are 5 main points that will help us understand diamonds better and make our purchases easier.

1. Report No.

The report number is basically an identification for each diamond, the number would match the engraving by laser on each diamond’s girdle.

2. Cut Grade

For the round shaped diamonds, we recommend looking mainly for Excellent, as cutting affects the diamond’s light reflection. For other shapes, most certificates usually include polish and symmetry, which are not as crucial. Trusting our naked eyes and choosing diamonds that we like are recommended for diamonds that are not round-shaped. (from GIA’s standard)

3. Proportions

These numbers are very very important ones, and they include:

• Table: Not too large, 57-59 is recommended for round diamonds.
• Girdle: Thin and medium are preferred, but the report no. would be smaller and harder to see.
• Total Depth: Not too shallow or deep, depending on other factors. Crown & Pavillion Angels: For round-shaped diamonds, 34-41 are the perfect pair for the most beautiful light performance (to Y. likings), as the refraction is good, making the face look wide.
• Culet: None is preferred.

4. Clarity Charactertistics

In a certificate, only ‘main’ inclusions are plotted. Other detailed information, such as inclusions are colored or if the inclusions are reflected itself within diamonds, or if the diamonds are green-tinted which are unique to diamonds from specific mines, would not be included. For this reason, we strongly advise everyone who is interested in purchasing a diamond to visit the store and see the real piece or buy from local stores that you can trust in order to get the best quality diamonds.

5. Fluorescense

For diamonds with high color range, ‘none‘ fluorescence would be the best choice. For the lower range of color from J and below, it could be a good pairing technique to choose those with a mild fluorescence as it helps make the diamonds look brighter.

Note:

• Diamonds with “IF” grade clarity (internally flawless) in GIA certificates are the same as “LC” (Loupe-clean) in HRD certificates.
• “None” Fluorescence in GIA certificates is “NIL” in HRD certificates.

Before buying diamonds, understanding what to look for in a certificate will help us understand the diamond’s qualities better. However, seeing the real piece before making the decision to buy is for the best, as some of the minor or smallest flaws might not be on the certificates but can be seen with closer inspection.

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	Written by Sornsida Y. Chanonprapa (G.D. GIA 2015)
	Diamond Nerd จากสถาบัน GIA ศึกษาเรียนรู้ หัด grading เพชรมาโดยเฉพาะ บวกกับพื้นฐานเป็นลูกช่างทอง มีประสบการณ์ทำงานใน Field จิวเวลรี่มากว่า 20ปี จึงอยากใช้พื้นที่นี้แบ่งปันความรู้และประสบการณ์กับทุกคนค่ะ