Gemological Institute of America 

What does the GIA Graduate Gemologist Diploma represent?  Who is  a G.G.? 

The prestigious GIA Graduate Gemologist diploma educates jewelers and appraisers the science and technical knowledge needed to evaluate the entire spectrum of diamonds and colored gemstones. The distinguished GIA GG designation is recognized around the world as the mark of a professional in the jewelry industry.

Buying a Diamond Wisely

1) Choose a jeweler as you would choose a doctor.

Your jeweler should be educated and have expert training, open to all your questions and provide answers with clarity.

A measure of a jeweler's knowledge is whether he is professionally trained. Preferably, his training comes from a highly-recognized and internationally accredited program, such as the GIA Graduate Gemologist (GG) or Accredited Jeweler Professional (AJP) diploma programs.

An educated jeweler will explain the 4Cs of diamond buying guide and demonstrate the differences between similar looking diamonds. The jeweler will have the ability to compare a number of diamonds within a specific price range.
2) The 4Cs of Diamond Quality

This basic knowledge will help you understand a diamond's value and price in an overall preview.

Diamond Color The absence of color ranks the diamond the highest for color rating; D-E-F. The less overall color hue in the diamond are subtle and these differences are sometimes not visible to the naked eye. Color hues directly impact the overall quality and price of the stone.

D-E-F Colorless, G-H-I-J Near Colorless, K-L-M Faint Yellow, N-O-P-Q-R Very Light Yellow, S-T-U-V Light Yellow

Diamond Clarity Clarity is the degree to which identifying characteristics known as inclusions are present in a diamond. Refers to the quantity, size and placement of internal inclusions and external blemishes. Grading diamonds based on inclusions are rated beginning with the most valuable termed, Flawless, a diamond that has no internal or external flaws visible under 10X magnification. Included, refers to a diamond with a significant number of imperfections.

Flawless Internally Flawless, No internal or external flaws visible under 10X magnification

VVS1-VVS Very Very Slight Inclusions, Inclusions are minute and extremely difficult to locate under 10X magnification

VS1-VS2 Very Slight Inclusions, Inclusions are minor and difficult to locate under 10X magnification

SI1-SI2 Slight Inclusions, Inclusions are noticable and relatively easy to locate under 10X magnification

I1-I2-I3 Imperfect, Inclusions are obvious under 10X magnification and are visible to the naked eye.

Diamond Cut Refers to the diamond's proportion and arrangement of its facets and the quality of overall polish, it does not refer the the shape of the diamond. The amount of brilliance, sparkle and fire in a diamond is determined by cut. Grades range from Excellent or Ideal, referring to an ideal proportion in which all light beams will be refracting back to the eye of the beholder from the top of the diamond, causing the diamond to sparkle. The lowest quality of cut is termed Poor, this may indicate that the facets are not the correct number or angles and the light beams will be refracted in different directions, to the eye the diamond will not sparkle well.

Diamond Carat Refers to a diamond's weight which is measured in carats, the standard world-wide measurement for a diamond size. Large Diamonds with high carat weight over five carats are rare and therefore, generally expensive. It is possible that several diamonds can be of equal carat weight and will vary considerably in quality, therefore, affecting the prices considerably. 

For an overall view, the 4 Cs are considered a good tool for a general evaluation.

3) Your  G.G. jeweler should provide a Diamond Grading Report with your purchase.

A diamond grading report from an unbiased, scientific source such as Gemological Institute of America is more than important information, it's proof of what you are purchasing. The differences in diamonds can be so subtle, your certificate will verify your purchase and is exclusive to your diamond.

4) Protect your purchase.

The jeweler should give you an appraisal for your diamond for insurance purposes. Insurers rely on diamond grading reports to accurately evaluate the value of gems and your appraisal document will allow you to replace your diamond from a jeweler of your choice in case of loss.

Jeff Deleuse, GIA Graduate Gemologist, Certified Appraiser and members of the 

American Gem Trade Association,  American Gem Society

Deleuse Jewelers, family owned and operated since 1945, in Fairfax, Ca


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“Janet, thank-you for everything you do. As I said before, you are truly an artist, and that is why it is so special buying jewelry from you.” Peter, Atlanta, GA

” Beauty, exquisite design, pleasant and personalized attention. These qualities have been constant in our 20 years of shopping with Janet and Jeff Deleuse – Two exceptionally talented and caring people. The Best!’ Helen P.,Belvedere

"This store has a very pleasant environment and Jeff and Janet are both kind, wonderful people. I used Jeff a few times for appraisals and he was very thorough and was happy to answer lots of questions. He uses scientific methods and tests rather than going solely by appearance as some jewelers will try to do, and his expertise is well respected. On one occasion, he even went out of his way to help expedite a deal for me. He has my highest recommendation. Suzanne T., San Rafael, CA

“Jeff is an incredible gemologist who knows everything there is to know about gem stones. He is a true professional and can be trusted. The quality of their work is impeccible and always consistent. I would recommend Deleuse Jewelers to anyone looking for a new, “bauble,” for themselves or someone special!” Terri B., Ross

"I have used Deleuse Jewelers for many years - for everything from purchasing jewelry to repairing jewelry to getting appraisals on jewelry. Their service and work is superb. I highly recommend them." Suzanne S., Tiburon, CA

"I purchased this beautiful chain from Janet Deleuse about 3 weeks ago. It was an online purchase so I was hoping I would be pleased. It exceeded my expectations as it was exactly as pictured. Delicate and perfectly crafted. Packing was very secure and shipping was quick. I would not hesitate to purchase from Deleuse again! Michele, New Jersey

“Janet and Jeff designed and crafted our wedding rings and did a great job. They worked with existing diamonds we had in an antique ruby cocktail ring, added the sapphire stone and made a beautiful pendant with the ruby. In addition, they designed earrings for our daughters. All are still in great shape today. They are easy to work with and very reliable and trustworthy.” Peg M., San Anselmo

Accreditation includes diplomas from the Gemological Institute of America and the American Gem Society and thirty years of experience.

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