Congrats! Nice find. As was stated, coticules can vary, but with the SRD stamp the odds are in your favor that it's a good one for razors I think. You done good. Here's one that I found at a flea market last summer in a box with a bunch of other stones. Also marked XX, but I think this one at 7 inches is the next size up? It's one of the best coticules I have. I worry about lapping it and losing the stamps though. Silly, I know... and eventually I will regard it for what it is, a tool, then I won't care so much about the stamps I suppose.
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