P in a circle mark could actually be the maker's mark. Irving M. Planick, 6 Maiden Lane, New York City.
About Platinum: Platinum is a white color, similar to white gold, HOWEVER, platinum will have a slight greyish tone. This beautiful metal was very popular in the early 1900's through the 1930's. Platinum is heavier than gold and more expensive. Usually a combination of 90% platinum and 10% iridium is used in jewelry.
Some platinum marks include: plat plat 10% irid platinum 950 950 Pt is the Italian mark for Platinum.
Do not confuse with Mexican silver. Some Mexican silver will be marked 950.
Testing Metal for Platinum:
The weight is often a good indicator. To confirm this use a touchstone and a platinum solution. If the acid does not dissolve the mark on the touchstone the piece is platinum. Your local jewelry can also test metal content.
Although we do not have a photograph, it certainly sounds like a beautiful heirloom engagement ring you have acquired. Thank you for writing in to us.... Yvonne Hammouda-Eyre If you would like to join the Antique Jewelry Investor community and stay up to date with all the latest Antique jewelry news, click here....
