@Al E. Gator - You are quite right that such a genuine, cut apart single might NOT cert based on the dimension requirements. That's exactly what I meant to suggest earlier. Just because it's too small to cert as a single doesn't mean it is not genuine. It just means that an expert can't give an opinion that it is genuine based on the evidence they have.
At least one or two alleged 315's without certs are available on
ebay almost every month, so there are a lot of small genuine singles, or trimmed perfed stamps, out there that will not cert.