Hi Dana thanks for writing in. That's an unusual mark. We know what 750 means, denoting 18K gold - 18ct or 750 (parts per 1000) or 75% gold. Most quality pieces are 18ct. Minimum gold standard for sale in Italy. It could be European.
ASA - The American Society of Appraisers, first came to mind, it's an international organization of appraisal professionals and others interested in the appraisal profession. ASA is the oldest and only major appraisal organization representing all of the disciplines of appraisal specialists. The society originated in 1936 and incorporated in 1952. ASA is headquartered in the metropolitan Washington, D.C., area, they have a great reputation but I don't think they are hallmarking their work yet :-)
If you could send in an image of the mark, another of the mark and surrounding area and a third image of the locket itself, I'll be happy to research this mark further. Also any info that might give us some indication of its age will help. Does it look modern or is it a vintage/antique piece?
The address to send images:
yvonnehammoudaATmac.com
AT=@
You might like to have a quick search in the US Jewelry Marks 1922 edition first, it's in the Jewelry Resources here...
