The quickest test is with a magnet. Unlike HSS, Stellite is *not* magnetic. All Stellite I've seen has been well marked by electro-etch, but it's possible you could find some that has had the marking removed, possibly from using the same end as the markings. Should you find any, don't pass it up. It's as close to carbide as you can get and not be there. It is ground with aluminum oxide wheels with no difficulty. It's wonderful stuff, but was replaced by carbide, which has a slight edge in some ways. Very unfortunate.
I had the good fortune to buy a small lot off ebay about two years ago. Unfortunately, what was sold was remnants that had been cut off from 1/2" squares, and were 1/2" shorter than the 3" represented. Fortunately, the markings are intact, so I know what they are. They aren't as long as I would have liked, but they are long enough to use. One of my goals was to grind a couple parting tools for deep cuts, but that isn't possible because of the short length. Sigh! Haynes Stellite is reputed to be tougher at red heat than at room temperature. Good stuff, Maynard.
Harold