This is a great ref book for Jewelry Companies that are long gone, their marks and company background. However it is missing some well known companies from the 50's and 60's but to it's credit there are also marks that ARE included that belong to little known companies. The layout could be improved as sometimes companies marked with a logo, and not the name, finding the logo means you have to search the whole book if you don't know who it was made by. That being said the book is a must have for all jewelry collectors as the info contained within is NOT the opinion of the author, it is taken from actual historical books, and vintage Trade guides etc.