The necklace measures about 18 and 1/16 inches long, from end to end, and will fit at about 18 inches long, but has an extra ring at 17 inches, to adjust the length to your preference. The chain is approximately 1.7 millimeters, or just over about 1/16 of an inch, wide. The central, fixed portion, (not including the two oval segments) measures approximately 1 and 5/8 inches wide, by just over about 3/4 of an inch high. (Included you will see a US Quarter in the photographs, for the measurement-challenged and ruler-averse.) It is stamped, "925", on the back of the central portion, unsigned, and marked, "925", again, on the spring ring clasp.
Weight is approximately 6.5 grams, which includes the stone weight, of course.
This necklace is in very nice vintage condition, with no kinks or bends. There will be the expected light surface scratches and tiny dings to the silver, from normal wear. No damage to the stone. Hand polished, but it may need further attention, especially to the back. The clasp works well and holds securely.
A gorgeous, nicely made, vintage Sterling silver and deep blue Lapis Celtic Knot necklace. A real standout.