From Beth Shaut of the Carder Steuben Shop in Corning, NY:
Mr Rockwell told me that in his early days of collecting, he had passed up some pieces because they had fake markings and said he wish he had bought them any ways because they were great examples. He also said that he bought a few pieces that were marked that weren’t Steuben so our motto in the shop was it didn’t matter if it were signed or not as long as we knew it was Steuben. Not everything was signed and certain things were never signed but given a sticker only. I suggest that if you are unsure of a piece that has a fake signature, talk to someone who knows the glass and verify it for you or pass it by.

Next, Keith Trippi of Grand Island, NY provides another insight.
A Club member said that they “recently passed on a nice piece of Carder Steuben because it had an engraved identification number on the bottom. I am wondering if other collectors would have bought the pieces.” The responses you published answered in the negative. My experience has been the opposite — engraved ID numbers can be an invaluable curatorial and conservation aid to the collector.

Engraved ID numbers can enhance value by establishing provenance. Collectors and museums may incise glass with an accession number to document and manage their acquisitions. If these pieces are subsequently de-accessioned, a crisp record is established of the chain of ownership, the so-called “provenance” of the object. This can be absolutely invaluable for research purposes, to establish or enhance value due to the prestige of the previous owner, and to prove ownership of the object.
A few years ago I took an engraved crystal vase that I own to a wonderful restoration studio for a very minor repair. When the work on my vase was completed, it was inadvertently packed and shipped to a glass dealer who coincidentally had many pieces of glass being repaired at the same studio at the same time. When the studio discovered what happened, they frantically contacted their customer, the art glass dealer, to recover my vase. This totally unscrupulous dealer had since sold my vase to another dealer boasting that the repair shop had made a mistake and he could sell my vase for so little because he had gotten it for free! Dealer #2 then resold my vase to dealer #3 who then resold my vase to a collector. I had four ways to prove title and ownership of my vase to anyone holding it adversely: (1) the original sales receipt, (2) photos of the vase (3) an engraved acquisition number on the bottom of the vase that uniquely identified it, and (4) the testimony of the repair shop and dealer #2 that the unscrupulous dealer never had clear legal title to my vase. My vase traveled all over the country, but I got it back in part because it could be uniquely identified with the permanently engraved ID number on it.

A reputable glass dealer should never be apprehensive about certifying to their buyer that they hold clean legal title to the glass they are selling. If an item has an identification number on it, have the dealer so certify title. If the dealer will not, do not buy the piece, because it may legally belong to someone else.

I ask all Club members who find fabulous glass but then pass on it just because it is engraved with an ID number to please contact me. I would be happy to own the undiscovered treasures you reject.