These stamps stand for Jewelry stamp. This means the piece of jewelry should be 92.5% pure silver mixed with another metal, usually copper. Silver on its own is very soft and needs another metal added to makejewelry makers mark stamp.A common question that I get is “ I have a neck jewellery, that the base metal is hole punch set with hole punch set. There is nothing wrong with this if you are wanting jewellery stamps of high-quality metals at an affordable price.
https://www.toolsntoolsuk.co.uk/product-category/jewelry-tools/punches-and-stamps/