A stone was found in Zhaotong, Yunnan, which is crystal clear and angular, and has many triangles and quadrangles. Is it a diamond?

Have you got any pictures? You can't tell without pictures.

There are many crystal forms of diamonds, depending on what happens.

The cut diamond is diamond luster, while the original diamond is oily luster, and there are often small triangular etching marks on the crystal surface. The biggest feature is not penetration, but hardness.

I think there may be something wrong with just looking at the angular features, not necessarily diamonds.