Diamond molds are tricky. With these, I can’t see an injection pip, but I’d have to handle them to know if they’re clay or plastic.
And plastic diamond molds—they’re not all created equal. I have some vintage 8.5g (scale confirmed) diamonds that rival 10g faux clays. They stack like a boss and they sound somewhere between a Bud Jones and a clay. I tried to the expand the set with some new ones from some vendor, but the new ones were 8.0g, unacceptably slick, and featured an insultingly limp sound.
So unless I can see flashing lines/scars on the edges, I check diamond molds in person.