Authentication of Rainpebbles Glass works

With immediate effect, Rainpebbles Glass is now uniquely marking our finished glass objects. We are doing this via the application of a hand-written signature which is unobtrusive (it is only visible when the piece is viewed at an angle, it is essentially invisible when the object is viewed via direct light). The signature is sandwiched within the glass layers of the piece, so it cannot be removed or modified without severely vandalizing the piece.
Each piece is uniquely numbered via a year/month/number ID.
We are doing this to assure clients that every piece is indeed unique (we have no production line round the back stamping these things out) and to document this within the finished piece.