All legitimate Steuben Glass pieces are signed in diamond script—usually on the bottom of the base. No pieces left the factory in Corning unless they were deemed 100% and properly signed. In the 1940’s-1950’s when most of the stemware and tableware items were produced, pieces were signed with simply a script S which is fine. The script S was also used on smaller pieces where it was impossible to fit the entire signature.
There is only one authoritative book on Steuben Glass: Steuben Glass—An American Tradition in Crystal by MJ Madigan and Abrams Press. This is a large history book with an important glossary in the back showing nearly all pieces produced up until 2001. The initial edition was printed in the early 1980’s but the better book is the 2001 edition because it contains the extra 20 years of history and glossary. In addition, the annual catalogues can be helpful in identifying pieces but they only contain the items that were currently in production. On line sources usually have these publications available.
The answer is very simple. Either use Windex and paper towels or dish liquid with lukewarm water only!!! Do not use hot water as pieces may crack under the heat.
If a piece of Steuben Glass is broken or becomes cloudy, there is no hope. However, if there are base scratches and/or small chips, as long as the integrity of the piece is not compromised, it is advisable to have the piece professionally polished by a reputable craftsman. It is not recommended that you have some “butcher” set up in the back of a show attempt to restore your items.
I purposely do not post prices on my website. However, if you inquire about items of interest, I will promptly reply with my fair market values. My prices reflect what I actually sell an item for in the marketplace and I do a lot of repeat and referral business because my prices are reasonable. Most importantly, remember that my pieces are always properly signed and in 100% condition---just like the day they left the factory in Corning!