The 10K solid gold handmade 2.5mm diamond-cut rope chain necklace, from Apples of Gold Jewelry, is available in 18" to 30" length and includes industry standard lobster claw clasp.
Once diamond-cutting is applied to the 3mm rope chain, actual measurement will be 2.75mm due to diamond-cutting.
Also available in 14k solid gold, shown below.
Gold weight varies based on length:
18 inches - approx. 11.05 grams
20 inches - approx. 12.15 grams
22 inches - approx. 13.15 grams
24 inches - approx. 14.33 grams
26 inches - approx. 15.50 grams
28 inches - approx. 16.65 grams
30 inches - approx. 18.06 grams
