German, second half 16th century

Overall the condition of the ring is very good with minor dirt and wear to the surface consistent with age. Much of the enamel survives. As is to be expected, there are some small losses to the enamel, in particular to the black enamel rays to the reverse; to the blue enamel at the sides; to the white enamel under the bezel; and to the red enamel at the strapwork on the band. The band is a little warped.
"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. Prospective buyers should also refer to any Important Notices regarding this sale, which are printed in the Sale Catalogue.
NOTWITHSTANDING THIS REPORT OR ANY DISCUSSIONS CONCERNING A LOT, ALL LOTS ARE OFFERED AND SOLD AS IS" IN ACCORDANCE WITH THE CONDITIONS OF BUSINESS PRINTED IN THE SALE CATALOGUE."

Compare the general form of this ring to one in the Victoria and Albert Museum set with a ruby (inv. no. 1731-1902) and another in the Ashmolean Museum, Oxford (inv. no. WA1897.CDEF.F465) with a jacinath, both dated to the 16th century. The reverse of the ring with its enamelled rays, central rectangular reserve and bezel junction compares to an example from the Ladriere collection (ex Guilhou; op. cit., no. 240, p. 249) and a ring of Mary Queen of Scots, known from an 1810 drawing (see Scarisbrick, 2007, op. cit., p.77). The fine high box setting intended to maximise the lustre of the precious stone, was preserved for the finest renaissance courtly jewellery, see for example such mounted diamonds on the Danish crown, dated to 1596 in the Rosenborg Castle Treasury (Hein, op. cit.). The whiteness of the diamond in this ring is associated with its principal sources at this time, the Golconda mines in India, whose diamonds were noted for their transparency and purity.

RELATED LITERATURE
D. Scarisbrick, Rings: The Jewelry of Power, Love and Loyalty, London, 2007, p. 77; J. Hein, The Treasure Collection at Rosenborg Castle, Chicago, 2009, part I, pp. 14-18; D. Scarisbrick, C. Wagner and John Boardman, The Ladriere Collections of Gems and Rings, Oxford, 2015, p. 249