We really need a picture. What diameter is it? Where did you get it from(location)?
The problem lies in the marking. While your example may be particularly clear, in many cases it is not, and what you think can be quite different from the truth. For example Sean O'Donohue from WA signs slightly differently just about every time I find a piece of his. Another artist signs BCG, or a stamp with a tree, rising sun and three bars, or ЯК where the two vertical lines are joined, or Rob Knottenbelt. All are the same person and while I know that it is from experience - having examples of each.
The range of knowledge is phenomenal on the GMB and there are likley to be people who recognise the actual signature just by seeing it.
If you are uncertain about posting pictures consult the reference section at the top of the GMB Index page. Instructions are clearly given there. Good luck - oh and by the way welcome to the board you will find it to be a great resource if you like glass.
Ross