Some items of jewelry are just so sublime that words only clutter them up, so I'll keep this as brief as possible.
This piece has absolutely no markings, yet it unquestionably tests as at least 18K gold (holds firm under 18k-test acid but dissolves at 22) with an exquisitely carved jadeite flower. (No mistake; it is harder than nephrite, testing solidly within the jadeite band on the Moh's scale, according to my Presidium 2 tester.) I surmise that this brooch was a bespoke piece, custom-made to order for someone well-to-do by a jeweler in? The jade would suggest China, but I can't be certain. And oh, my—this jade! For jadeite, it's unbeliebeably translucent, and has gorgeous variegation of color, all of which makes its value higher. The bud has a gold center, and the flower itself is carved to super-real detail, having straight striations running the length of its asymmetrical petals. This flower is far more netsuke-like than most Chinese work I've seen, and correct me if you know better, but I'm leaning toward Japan as being its birthplace.
DISCLOSURE: the once-rolling C clasp is broken: The tiny part that rolled to close it has fallen out. However, there is enough tension in the pin that it catches securely inside the C and I had no qualms about wearing it as-is. Normally I have such things repaired before selling them, but I wanted to leave the choice to you and in so doing, keep the brooch's price as low as possible. Should you wish it repaired, a jeweler may not even need to use laser to replace the clasp part, but even if s/he does, the charge will be approximately $50-100.
The flower bud, at its tip's broadest point, measures .75 inch (19mm) in diameter. At its narrowest diameter it is 5/8" (15.87mm) wide. In legth from its base, the distance is close to 9/16" (14.28mm) to the inside cuts (the indented Vs) of the flower, while the length to the flower petals' tips ranges from a tad over 5/8" to .75" (15.87-19mm), which coincidence of symmetry may not be accidental. This flower was plainly carved by a Master craftsworker, no apprentice. It is flawless save for a very small marking which may be an inclusion in the stone; I cannot see any surface abrasion or crack to signal trauma, so my inclination is that it's a natural inclusion. (See pic .) The length of the piece is 2 & 7/8" () and the brooch is approximately an inch () wide at it's leaf's center curve.
Please examine my photos to fill in any blanks, and msg me with possible Qs. I'll gladly respond ASAP.
Weight: 10.7 grams.