- Platinum provides the best, most neutral white colour of all the jewellery alloys. Some new white gold alloys come close, but nothing is as white as platinum for most purposes. This is especially true for a diamond setting, since its pure colour accentuates the sparkle and brilliance of the stone without reflecting any colour in it.
- It takes approximately 10 tonnes of platinum ore to produce one ounce of pure metal. By comparison, it only takes three tonnes of ore to produce one ounce of gold. This contributes to platinum’s appeal as a luxury metal. Platinum is 50 per cent more dense than 18-karat gold, giving a platinum piece a satisfying ‘heft.’
- Platinum has a much higher melting point than gold. This permits the creation of two-tone designs by starting with a platinum component and later casting or fusing yellow gold accents without affecting it.
- Platinum alloys used in jewellery applications are usually 90 to 95 per cent pure and incorporate one or more of the other platinum group metals, while the majority of gold jewellery contains a maximum of 75 per cent pure gold, which further adds to platinum’s luxury cachet.
- Most platinum alloys will not tarnish, even when heated to white hot. This is a major advantage during fabrication and finishing, since it is possible to pre-polish a component prior to soldering or welding it to another component. This is not possible with gold alloys, which oxidize when heat is applied.
- Hand-fabricated platinum jewellery takes full advantage of the inherent tensile strength of the metal, allowing a jeweller to create incredibly delicate elements that are still durable and hard-wearing.
- Provided they are adequately informed, most consumers will appreciate the patina of surface scratches that result from normal wear. Although they can be removed by polishing, the natural patina that develops actually lets gemstones take centre stage, while the metal provides a more subtle supporting role.
- Platinum is a poor conductor of heat, which can give it an advantage over gold during assembly using a torch and especially with the laser welder.
- Platinum is hypoallergenic, meaning it can be tolerated by almost everyone, even those who otherwise react to other metals when in close contact with their skin.
- “¨Its ductility and malleability offer advantages in strength and durability, especially for securing gemstones in fabricated items. There is less ‘spring’ to the metal and a claw pushed over a gemstone does not bounce back the same way a more brittle white gold claw does. Platinum claws do not work-harden as quickly as white gold, and there is less chance of a claw simply shearing off due to internal stress.
- A platinum piece has greater long-term durability, even though it may appear more delicate than a similar gold item. That’s because the metal compacts and compresses with time and wear, and actually increases in strength. White gold is rather brittle and abrades much more quickly.
- Some clients find the greater weight of a platinum piece uncomfortable.
- “¨Platinum is more expensive than white metal alternatives, although since cost is actually driven by its use in the auto sector, the metal has occasionally dipped below the per-ounce price of gold, particularly in a tough economic climate and during slumps in the auto industry. Platinum is also more dense than gold, which means it takes more pure platinum than pure gold to craft the same piece of jewellery. This drives the final price well above karat gold.
- Platinum takes longer to finish and polish. Although its malleability is an advantage for long-term wear, it also means the goldsmith must use ever-finer grades of sandpaper prior to abrasive compounds on the polishing lathe and the final polish with rouge. Any minor surface flaw is simply magnified as the polishing process proceeds. This requires both higher skill level and simply more time to achieve a perfect finish. The extra time factors into the increased price, as well.
- Platinum’s high melting point requires proper torches and casting equipment, as well as special investment and technique. Platinum must be kept separate from other metals to avoid contamination. A tiny piece of steel or gold can become incorporated into a piece of platinum and ruin it. Refining of scrap metal is very expensive and you need a large amount of scrap to make it economical. This adds to the cost of using platinum.
- When cast by an inexperienced craftsman, platinum is rather soft and porous. I compare it to sponge toffee candy. It may look fine after finishing and polishing, but within a few weeks of normal wear, it starts to compact and compress and looks like it was beaten with a hammer. This can be a problem in particular with large cast pieces or those that are blocky solid forms.
Creative metallurgists, such as the late Steven Kretchmer, developed platinum alloys that solved some of the issues with cast designs, as they can be hardened post-casting by using a specific protocol of heating and cooling. These alloys permit durable tension-style settings that were not practical with traditional mixes. However, some of these oxidize with heat, which requires extra steps to remove in the final finishing steps. In addition, some of them are slightly magnetic, which must be taken into consideration to avoid contamination with fragments of ferrous metal. This property was exploited by Kretchmer with another special alloy incorporating floating components that appear to defy gravity.