Published 2 June 2026
The 750 number
18 carats in the 24-carat scale is 18 divided by 24, which is 75% by weight, or 750 parts per thousand. That is what the punch records: three quarters of the alloy is pure gold.
Typical recipes: 18ct yellow is roughly 75% gold, 12.5% silver, 12.5% copper. 18ct rose pushes the copper up. 18ct white uses palladium instead of silver, with rhodium plating for the bright finish.
Where you see 18ct
Signed designer jewellery, Cartier, Tiffany, Bulgari, Boodles, Boucheron, premium British and European retail brands, and most signed engagement rings sit at 18ct. The colour is richer because there is more pure gold, and the marketing weight of "fine jewellery" sits at this karat.
You will also see 18ct on heavy gent's signets, on dress watches, on premium chains and on bullion-style jewellery items intended to hold both wear and value.
Wear, scratch and dent
How 18ct sells at scrap
Recovered gold per gram on 18ct is substantially higher than 9ct or 14ct because the gold percentage is twice that of 9ct. Refiners process 18ct routinely, the recovery yield is high, and the market for it is deep.
Where designer 18ct has resale value beyond the gold (a signed Cartier love bracelet, an antique 18ct mourning brooch, a rare watch), the piece is worth more sold whole than melted. A written XRF valuation gives you the scrap floor in writing so you can negotiate the resale price against that floor.
Final offers depend on inspection, item weight, purity, hallmarks, stones, non-gold components, condition and the live precious-metal market.
Identifying 18ct quickly
- Find the standard mark inside the shank or on the clasp.
- Look for "750" inside a shield punch, or "18ct", "18K", "18kt" on imported pieces.
- Look for the matching UK assay office mark beside the standard (leopard, anchor, rose, castle).
- On signed designer pieces, locate the signature alongside the hallmark and document it for resale value research.
- When marks are gone, post it for XRF. Designer pieces benefit especially from the written report because it confirms metal content for any future resale.
Sending 18ct by post
18ct posts the same as any other gold karat. The XRF report shows the alloy and the weight, the bank transfer settles the offer, and decline is free tracked return. Your parcel is insured up to £2,500 via Royal Mail Special Delivery. See how to sell gold by post.
Signed pieces are weighed and identified individually so you can choose to accept the scrap offer or withdraw the piece for a private resale.
A different close
18ct is where the gold market and the fine-jewellery resale market overlap most. The scrap recovery is generous because the gold content is high, but a Cartier bracelet on a signed plaque is often worth more sold whole. The right move depends on the piece. A written XRF report puts the scrap floor on paper so you can compare it to any auction estimate before you commit. That is the value of testing before selling, every time.
Common questions
Is 750 the same as 18k?
Yes. 750 is the parts-per-thousand UK standard mark; 18k is the US karat designation for the same purity.
Why is 18ct softer than 9ct?
Less base metal in the alloy. Pure gold is very soft, so the more gold there is by percentage, the softer the alloy.
Does 18ct hold its colour better than 9ct?
Yes. The richer yellow comes from the higher gold content and resists colour shift over time.
Is 18ct better value than 9ct at scrap?
Per gram, yes. Per piece, mass and item weight matter. A heavy 9ct chain can outpay a light 18ct ring even at lower karat.
Can I sell a Cartier 18ct piece for scrap?
You can. You may not want to if the signed resale price beats the scrap floor. The written valuation tells you the floor in writing.
Does GoldPaid handle 18ct watches?
18ct watch cases are valued on the gold content. Movements are returned with the parcel if you decline the offer or sold separately by you.
Why are some 18ct chains stamped only "750"?
The three-digit standard is sufficient identification under UK hallmarking. Foreign pieces stamped only "750" lack the UK assay office mark, but the XRF result is conclusive.
Is 18ct white gold worth the same as 18ct yellow?
Yes. Same standard, same recovered gold per gram, same scrap figure at the same market level.