As for the 18K gold necklace made in Italy, how much is it worth? It depends on the style, preservation integrity, length and thickness of the necklace. It's hard to estimate without photos.

18K: pure gold 750, silver-copper alloy 250.

22K: pure gold 9 17, silver-copper alloy 83 ternary alloy.

24K: pure gold 1000.

SV925: (called "pure silver" in Europe and America, binary alloy of pure silver 925 and copper 75).

SV 1000: pure silver. Pt900: Binary alloy containing 900 platinum and 100 palladium.

Pt850: ternary alloy of platinum 850, palladium and copper 150.

Gold: Yellow precious metal. Pure gold 999 is generally called 24K, with soft texture and strong plasticity.

K gold, a bright yellow precious metal alloy, is not easy to make exquisite jewelry because of its soft texture. It is composed of gold (Au), silver (Ag) and copper (Cu). Used as an inlay alloy for high-grade jewelry, grades are distinguished by gold content. The gold content of 750 is called 18K, the gold content of 585 is called 14K, and the gold content of 500 is called 65433.

Platinum: A white alloy that replaces platinum. It is a white alloy composed of gold (Au), palladium (Pd) and silver (Ag). Because its appearance color is quite similar to platinum, it is not easy to distinguish in appearance, and it is often mistaken for platinum, but there is a clear gap between them in texture and weight. Platinum is higher than platinum in texture density and commodity value, but platinum has a price.

Platinum: Also known as pure white gold, positive platinum or true platinum. But these names are unreasonable and easily confused with platinum. Its symbol is Pt, silvery white, its specific gravity is 2 1.35, its melting point is 1.700℃, its Mohs hardness is 4-4.5 degrees, its chemical properties are stable, and it is not corroded by acid and alkali except aqua regia.

Pure platinum is relatively soft, and the addition of metals such as ruthenium, rhodium and palladium will increase its hardness.