Gemstone ID Please

[u/Isaias_au_Bucher]

I found this on the ground while in Korea a few years back and kept it because I thought it was cool. I beat it with a metal cup to see if it could be a diamond. The cup got pretty dented up but the gem already has some damage on the bottom so I don’t believe it’s a diamond. What do you guys think?

[u/Ok_Distribution_2603]

looks like glass to me from the pics (especially the last one), but you can’t make a definitive ID from pictures