750 Gold (18 Karat)
Also: 18 carat gold, 18k, 750, Au750
750 gold is a gold alloy with a fineness of 750 per mille (75.0 %), equal to 18 carat, and the most widely used quality in the jewellery and watchmaking industries.
750 gold - colloquially "18 carat gold" - is the dominant quality grade for premium gold jewellery and luxury watches worldwide. With a gold content of exactly 75 per cent, the alloy strikes a convincing balance: it stays rich enough to keep the characteristic warm gold colour and a high metal value, yet is far more robust than almost-pure fine gold (999). The melt value calculator helps you find the current metal value of an 18ct piece in seconds.
Fineness and the carat system
The fineness states how many grams of pure gold are contained in 1,000 grams of an alloy. In 750 gold that is 750 of 1,000 parts - three quarters. In the carat system this corresponds to exactly 18 of a possible 24 carat, since by definition one carat equals one twenty-fourth of the total weight.
Fineness () = (carat / 24) x 1000
750 = (18 / 24) x 1000
The remaining 25 per cent of the weight consists of one or more alloying metals. It is their composition that decides the colour, hardness and other properties of the finished piece.
Alloy variants and colours
Depending on the mix of additional metals, visually very different gold qualities emerge - all bearing the same 750 stamp:
| Colour | Gold content | Main additions |
|---|---|---|
| Yellow gold | 75 % | Silver (~12.5 %), copper (~12.5 %) |
| White gold | 75 % | Palladium or nickel, optionally zinc |
| Red gold | 75 % | Copper (raised share, ~22 %) |
| Rose gold | 75 % | Copper (~20 %), silver (~5 %) |
| Green gold | 75 % | Silver (raised share), no copper |
White gold with a palladium addition is now regarded as the skin-friendly standard variant, because nickel white gold can trigger allergic reactions. Palladium white gold is often additionally rhodium-plated to brighten its slightly greyish natural tone and make the surface more scratch-resistant.
Hallmark and marking
Every reputably made 750 piece carries a hallmark documenting the fineness. In Ireland and the EU the mark 750 (per-mille stamp) or 18K (carat stamp) is customary. British pieces show the hallmark with the number code 750; older continental European pieces occasionally bear the signature Au 750. A missing or illegible stamp is no guarantee of quality either way - when in doubt an X-ray fluorescence analysis provides clarity.
Calculating the melt value
The material value of a 750 piece can be derived from the current gold price and the weight of the item:
Melt value = weight (g) x 0.750 x gold price (EUR/g)
Example: a ring weighs 6.0 g and the gold price is EUR 85.00/g.
Melt value = 6.0 x 0.750 x 85.00 = 382.50 EUR
The gold calculator performs this sum automatically at the day's live price. When selling to a buyer, the price actually paid is usually a little below the melt value, since melting and processing fees arise. The buying price calculator shows realistic comparison figures.
750 gold in dentistry
Historically, 750 gold was also common in dental technology. Classic dental gold alloys for crowns, bridges and inlays frequently contain exactly this fineness, supplemented by platinum, palladium and silver for greater strength and biocompatibility. Anyone wanting to recover old dental work can use the dental gold calculator to estimate the approximate metal value.
Comparison with other finenesses
| Alloy | Fineness | Carat | Typical use |
|---|---|---|---|
| 333 gold | 333 | 8 kt | Entry segment, fashion jewellery |
| 375 gold | 375 | 9 kt | UK and Irish jewellery market |
| 585 gold | 585 | 14 kt | Mid-range jewellery, USA |
| 750 gold | 750 | 18 kt | Premium jewellery, watches |
| 916 gold | 916 | 22 kt | Bullion coins, Asian jewellery |
| Fine gold | 999 | 24 kt | Bars, bullion coins |
750 gold sits firmly in the premium segment. Against the widespread 585 grade, its gold content is about 16.5 percentage points higher (75 % versus 58.5 %) - which is clearly reflected in the metal value and explains the marked price gap between the jewellery segments.
Buying, selling and tax notes
750 jewellery and watches with 750 gold cases trade well on the secondary market, because the fineness is internationally recognised and easily verifiable. At retail the price always includes, on top of the melt value, a surcharge for craftsmanship, design and trade margin. On resale, by contrast, it is chiefly the metal value that is reflected.
For a private seller in Ireland: any gain on the sale of jewellery and precious metals is chargeable to Capital Gains Tax at 33 %, after the annual personal exemption of EUR 1,270. There is no holding-period relief - unlike Germany's one-year rule under Paragraph 23 EStG, the gain remains chargeable regardless of how long the item was held. Note: this is not tax advice; for binding information contact the Revenue Commissioners (revenue.ie) or a qualified adviser.
Where a dealer takes a cash payment of EUR 10,000 or more, anti-money-laundering obligations apply under the Criminal Justice (Money Laundering and Terrorist Financing) Act 2010 - meaning identity verification by the dealer.
In brief
750 gold (18 carat) combines a high fineness of 75 % with good workability and everyday durability - no wonder it is the preferred choice of goldsmiths and watchmakers worldwide. To learn the current metal value of a piece, the best tool is the melt value calculator with the live gold price.