I have just found this site which I though might be of help at one time or another.
I am researching a brooch with only numbers as hallmarks. since I have had pieces with pat. numbers I thought I would give it a try and I stumbled upon this site.
Please share with us any useful sites for help and identification you may find.
Susan, it's a great idea to have a "one-stop shop" of jewelry research links. Here are five of my most frequently used ones:
Researching Costume Jewelry - RCJ = https://www.illusionjewels.com/research/costumejewelrymarks.html. This is the FIRST place you need to go if you see a signature you don't recognize.
Sandy Carroll's "Dangles" site, http://imageevent.com/flippingtreasures/identifieddangles/abcde. Sandy is one of the most helpful and knowledgeable people on the eBay Jewelry Board Group, and she set up this album to list "dangles" - the large bead or ornament on hook-and-extender necklaces that keeps the hook from sliding off. Some are common, but others are company-specific. She also has a page on identifiable back textures such as the 1928 Jewelry Co. swirls.
Cathy Gordon, http://imageevent.com/bluboi. Cathy literally wrote the book on Miriam Haskell, and has a lot of very valuable information on Haskell findings and construction. Before you claim a mystery piece is Haskell, it's a good idea to look through Cathy's Haskell albums. She also has albums on suffragette jewelry, Takahashi birds, and more.
Is It Juliana Jewelry, http://www.isitjulianajewelry.com/. Searchable database of verified Juliana/D&E pieces. Also http://www.agedandopulentjewelry.com/pages/JulianaJewelry.htm - they don't do verifications any more, but their albums and articles on construction are great ways to educate yourself about Juliana.
Online Encyclopedia of Silver Marks, Hallmarks and Makers' Marks, http://www.925-1000.com/. Silver marks from all over the world.