See description in first or three items subitted.
Shape (debatable) - large leaf. Length = 27mm. Width (widest) = 16mm, Mass = 6.98 ct
An Unmounted Opal, Australian
the transparent stone carved in the shape of a leaf, weighing 6.98ct, displaying blue and green flashes, 27 x 16mm.
Provenance: According to the owner this opal was purchased from Bruno Moser, W. B. Moser PTY. LTD. Trade International between 1975 and 1982 in one of numerous trips to Australia. He employed sculptures and artists to create designs like this. All opal in my collection was directly purchased at or near the mines in the Coober Pedy region. The company appears to be in business and located in Burnside, Australia.
This appraisal is worthless, I have had offers in excess of $16,000 USD from a jewelry store owner for this stone. You clearly are not qualified to make this appraisal.