Hi AK thanks for writing in. Ok - Crowns do not always mean British. Crown followed by 18, Crown followed by 22 are both British gold standard marks used between 1798 - 1974 and 1844 - 1974 respectively.
Our guests find the Jewelry Resources a really useful information resource. You might like to try searching under "US Jewelry Marks 1922" - From the Jeweler's Index 1922 edition in the Jewelry Resources.
You mention the Georgian Jewelry contains Colored diamonds, in particular Black Diamonds. You are very fortunate to have acquired such a piece. Black diamonds mainly come in grays, not truly black. Fancy black diamonds of fine color and clarity are rare. They have a magnificent sub-metallic luster, some black diamonds actually look like black wax.
We have had many guests in the past, asking about X marks on their Jewelry. You will be able to find this information by searching the X mark on this site at Jewelry Sitesearch
