Pure Gold
Pure Gold
The 24-karat baseline against which every other gold alloy is measured
Pure gold is gold in its highest commercial fineness, conventionally specified at 99.9 per cent (999 parts per thousand) or higher and designated 24 karat. The remaining 0.1 per cent or less consists of trace contaminants — silver, copper, palladium, or other metals — that survive the refining process; further refining to 99.99 per cent (four-nines) or 99.999 per cent (five-nines) is achievable for investment-grade and electronic-grade applications. The metal is the chemical element gold (Au, atomic number 79) in its essentially undiluted form, and it is the foundation from which every alloyed gold variation in the jewellery and bullion trades is built.
Properties at the bench
Pure gold is exceptionally soft for a structural metal, with a Mohs hardness of 2.5 to 3 — comparable to fingernail and easily marked by ordinary handling. Its tensile strength is similarly modest, and a piece of pure gold worked to a thin section will deform under the slightest pressure. The metal is, however, extraordinarily ductile and malleable: a single gram of pure gold can be drawn into a wire over three kilometres long, or beaten into a leaf one ten-thousandth of a millimetre thick covering an area approaching a square metre. The colour is the unmistakable warm yellow that defines gold in the popular imagination, with no significant variation by source or refining method.
The melting point is 1,064 degrees Celsius. Pure gold does not tarnish under normal atmospheric conditions and is essentially inert to most acids and bases, with the principal exception of aqua regia (the nitric-and-hydrochloric mixture historically used to dissolve gold for refining) and certain cyanide solutions used in electroplating. The combination of inertness and visual permanence is the chemical basis for gold's role across human history as a store of value, and it is why ancient gold jewellery from the Egyptian, Mesopotamian, Greek, Etruscan, Roman, and Byzantine traditions survives in essentially the same metallic state in which it was made.
Use in jewellery
The softness of pure gold makes it unsuitable for most contemporary jewellery applications, where the metal is expected to support stones, take a wearable polish, and resist deformation under daily use. The metal is too soft to hold prong settings reliably or to resist the abrasion of routine wear, and pieces fabricated in pure gold for everyday use will deform within months. Pure gold is therefore alloyed for jewellery use, with the standard fine-jewellery alloys at 22 karat (91.6 per cent gold) for high-karat traditional jewellery, 18 karat (75 per cent) for the dominant fine-jewellery standard in Europe and most international markets, 14 karat (58.3 per cent) for the dominant North American mid-market standard, and 10 karat (41.7 per cent) as the lowest legal designation for gold in the United States.
The exception is the high-karat tradition of South Asian, Middle Eastern, and East Asian jewellery, where 22-karat and even 24-karat pieces are produced and worn for cultural, religious, and investment-store purposes. Indian wedding jewellery, Middle Eastern ceremonial jewellery, and Chinese chuk kam gold (literally "pure gold," with a fineness of 99.9 per cent or higher) are the major commercial categories of high-karat and pure-gold jewellery in the modern market.
Bullion and investment
Outside the jewellery trade, pure gold is the standard form for investment-grade bullion. The London Bullion Market Association (LBMA) Good Delivery standard requires bars of 99.5 per cent purity or higher; investment coins from major mints (the South African Krugerrand, the Canadian Maple Leaf, the American Eagle, the Austrian Vienna Philharmonic, the Chinese Panda) are produced at 99.99 per cent purity in standard sizes from one-tenth ounce upward. The pure-gold form is preferred for bullion because it eliminates uncertainty about the underlying gold content and because the price is universally referenced to the gold spot price without alloy adjustments.
In the trade
For Skyjems, a private dealer working primarily in coloured stones and high-karat jewellery, pure gold is the commercial baseline against which all alloy decisions reference. A bespoke piece can be commissioned in 24-karat, 22-karat, 18-karat, or 14-karat depending on the customer's preference for warm yellow colour (favouring high karat), wearability (favouring lower karat), or jurisdiction-specific hallmarking conventions. Pure gold ingots and grain are routinely used as the starting material for in-house alloying when a workshop blends its own colour-specific or fineness-specific gold for a particular project. The 24K hallmark is the universal standard designation, recognised by GIA, AGTA, the London Assay Office, and every other major hallmarking authority worldwide.