A stone of that size and quality find fair value from about...

A stone of that size and quality find fair value from about US$420ct.

But it depends on the quality and look of the stone.

For example, a 1.2ct octahedron crystal (cutable), VS2, colour 'H' should find fair value around AUD$670 (incl. GST)

On the other hand, a 1.2ct octahedron crystal (cutable) IF, colour 'D' should find fair value around AUD$1400 (incl. GST)

So, in answer to your question, I guess I am prepared to pay from about $700 to $1500 for the stone...depending on size, shape and quality.

Regards.