Simple Online Photographic Dictionary
a visual dictionary that can be used as a children's picture dictionary,an English language learning tool or a cross-cultural reference.

A diamond, or rhombus is a four-sided shape, like a square turned on its side. All four sides of a rhombus are the same length but the angles on the corners do not have to be 90 degrees like in a square, the rhombus can be taller than it is wide or wider than it is tall.
The gemstone in the picture is diamond-shaped.
A diamond is also a kind of stone.