The cushion-shaped sapphire weighing 24.76 carats, the shoulders set with baguette and keystone-cut diamonds within borders of numerous small round diamonds altogether weighing approximately  1.25 carats, mounted in platinum, size 5¾. 

See AGTA report no. 92024110 stating that the sapphire is of Kashmir origin; no indications of heating. AGL report no. CS 38803 stating that the sapphire is of Kashmir origin; no gemological evidence of heat enhancement present. Gubelin report no. 0703640 stating that the sapphire is of Kashmir origin; no indications of heating. The diamonds are approximately F-G color and VVS-VS clarity. In very good condition.
In response to your inquiry, we are pleased to provide you with a general report of the condition of the property described above. Since we are not professional conservators or restorers, we urge you to consult with a restorer or conservator of your choice who will be better able to provide a detailed, professional report. Prospective buyers should inspect each lot to satisfy themselves as to condition and must understand that any statement made by Sotheby's is merely a subjective qualified opinion. Illustrations in the catalogue may not be actual size. Prospective purchasers are reminded that, unless the catalogue description specifically states that a stone is natural, we have assumed that some form of treatment may have been used and that such treatment may not be permanent. Our presale estimates reflect this assumption.
NOTWITHSTANDING THIS REPORT OR ANY DISCUSSIONS CONCERNING CONDITION OF A LOT, ALL LOTS ARE OFFERED AND SOLD "AS IS" IN ACCORDANCE WITH THE CONDITIONS OF SALE PRINTED IN THE CATALOGUE.

Accompanied by three gemological reports:

AGTA report no. 92024110 stating that the sapphire is of Kashmir origin; no indications of heating.

AGL report no. CS 38803 stating that the sapphire is of Kashmir origin; no gemological evidence of heat enhancement present. 

Gubelin report no. 0703640 stating that the sapphire is of Kashmir origin; no indications of heating. The Gubelin report is accompanied by a letter stating:

"The natural sapphire of 24.76 ct described in the above mentioned Gubelin Gem Lab Report possesses a richly saturated and homogeneous colour, combined wth a high degree of transparency, and a finely proportioned cut. In addition, this remarkable gemstone has been spared of thermal treatment.

Such a combination of characteristics is rare in natural Kashmir sapphires of this size." 

This lot will also be accompanied by a hardbound book, published by the American Gem Trade Association Laboratory, on the subject of Kashmir sapphires.