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Jewelry, Gems, & Minerals/Stamps inside a sapphire ring


Would like to know what 375 CR and the other one is GM52 these r stamped either side of the inside of my ring

Most experts here do no try to answer questions on makers marks because unless we happen to recognize the mark right off, we have to search to find an answer, just as you would have to do. There is one mark which applies to metal quality, the 375.  This is not  a makers mark bug indicates the ring is 9 karat gold.  It is showing how much pure gold is in the alloy.  24k is pure gold.  375 represents actually 0.375 for pure gold in the mix. From this we get 0.375 x 24k = 9k.

The other marks are manufacturers marks, CR being the abbreviation for the maker.  The GM52 might be a style number or represent something else entirely. On that one, we simply do not know the meaning.

God Bless and Peace. Merry Christmas.  Thomas.  

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Have a question about jewelry repair or working with precious metal jewelry and gemstones? For many years up to December 31, 2010, I was a working professional bench jeweler, involved everyday with setting stones in mountings, designing and making jewelry, repairing and limited custom manufacture. If you work with jewelry as a hobby or as a profession, I might be able to help. I deal with the retail business, not mass production. Ask privately if you wish. See the box for that: It keeps your question between us. Please DO NOT ask MAKER'S MARKS, but metal quality marks are fine to ask. Please DO NOT ask diamond prices. See a gemologist for that.


I have extensive experience in design, service and making of jewelry. I deal mostly with precious metals and gemstones but work with many materials as needed and usable to create an artistic design. My experience also includes freelance photography and photographer of jewelry and similar items for a former employer and individuals. Design of custom items requires reading the desires of the client and being clear on what can be done within that framework...then fulfilling the transition of idea to reality. Effective communications is essential in a working designer/producer and customer relationship.

Education is English/Physics! Started in human resources, to advertising, to, what a road. I have had formal training in jewelry work and many shared experiences with top grade jewelers. We just never know were we will go or be. Follow your best, your dreams, with some discretion! Don't let the work tear up your body along the way as it has mine.

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