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Ornate emerald and diamond coronet cluster ring. Set to the centre with an octagonal emerald-cut natural Colombian emerald with no colour enhancement in an open back rubover setting with an approximate weight of 0.60 carats, surrounded by twenty round old cut diamonds in open back grain settings with a combined weight of 1.40 carats, flanked by twelve round old cut diamonds in open back grain settings with a combined weight of 0.36 carats. The total approximate diamond weight is 1.76 carats, to an octagonal form featuring extremely ornate pierced scrolling metalwork and millegrain borders, supported by a conforming gallery with cheniers and intricate backholing, flanked by trumpeting shoulders and terminating in a slim grooved shank. Marked iridium and platinum, American, circa 1920, accompanied by Gemmological Certification Services report #79178-10.
Inside diameter (mm) |
USA | UK | China India |
European |
---|---|---|---|---|
11.63 | 0 | |||
11.84 | ¼ | |||
12.04 | ½ | A | ||
12.24 | ¾ | A½ | ||
12.45 | 1 | B | 1 | |
12.65 | 1¼ | B½ | ||
12.85 | 1½ | C | ||
13.06 | 1¾ | C½ | 41 | |
13.26 | 2 | D | 2 | 42 |
13.46 | 2¼ | D½ | ||
13.67 | 2½ | E | 3 | 43 |
13.87 | 2¾ | E½ | ||
14.07 | 3 | F | 4 | 44 |
14.27 | 3¼ | F½ | 5 | 45 |
14.48 | 3½ | G | ||
14.68 | 3¾ | G½ | 6 | 46 |
H | 47 | |||
14.88 | 4 | H½ | 7 | |
15.09 | 4¼ | I | 48 | |
15.29 | 4½ | I½ | 8 | |
15.49 | 4¾ | J | 49 | |
15.7 | 5 | J½ | 9 | 50 |
15.9 | 5¼ | K | 51 | |
16.1 | 5½ | K½ | 10 | |
16.31 | 5¾ | L | 52 | |
16.51 | 6 | L½ | 11 | |
16.71 | 6¼ | M | 12 | 53 |
16.92 | 6½ | M½ | 13 | |
17.12 | 6¾ | N | 54 | |
17.32 | 7 | O | 14 | 55 |
17.53 | 7¼ | O½ | 56 | |
17.73 | 7½ | P | 15 | |
17.93 | 7¾ | P½ | 57 | |
18.14 | 8 | Q | 16 | |
18.34 | 8¼ | Q½ | 58 | |
18.54 | 8½ | R | 17 | 59 |
18.75 | 8¾ | R½ | ||
18.95 | 9 | S | 18 | 60 |
19.15 | 9¼ | |||
19.35 | 9½ | S½ | 19 | 61 |
19.56 | 9¾ | T | ||
19.76 | 10 | T½ | 20 | 62 |
19.96 | 10¼ | U | 21 | |
20.17 | 10½ | U½ | 22 | 63 |
20.37 | 10¾ | V | 64 | |
20.57 | 11 | V½ | 23 | |
20.78 | 11¼ | W | 65 | |
20.98 | 11½ | W½ | 24 | |
21.18 | 11¾ | X | 66 | |
21.39 | 12 | Y | 25 | 67 |
21.59 | 12¼ | Y½ | 68 | |
21.79 | 12½ | Z | 26 | |
22 | 12¾ | Z½ | 69 | |
22.2 | 13 | 27 | ||
22.4 | 13¼ | |||
22.61 | 13½ | |||
22.81 | 13¾ | |||
23.01 | 14 | |||
23.22 | 14¼ | |||
23.42 | 14½ | |||
23.62 | 14¾ | |||
23.83 | 15 | |||
24.03 | 15¼ | |||
24.23 | 15½ | |||
24.43 | 15¾ | |||
24.64 | 16 | |||