unusal shape

[climbingone]

I have seen a Diamond that looked round until you looked through a loupe and it appears to have about sixteen facets around the outer edge and the girdle is a zigzag pattern up and down what is this cut called I have never seen it before

 

[Circe]

I'm having a hard time visualizing this - could you upload a sketch, maybe?

 

[davi_el_mejor]

Since diamonds are cut using straight lines/planes... your "round" is actually something more like a hexadecagon or a 16 sided polygon. From normal viewing distances your eye smooths out all the corners and makes it round.

As for the zigzags in the girdle, it could very well just be a faceted girdle.