Platinum

Platinum is a dense (heavy) hard silvery metallic element.
Atomic Number: 78
Atomic Weight: 195.08
Density or Specific Gravity: 21.45
Melting Point: 1768.90 Celsius
Hardness (Moe) 4.3
Although Platinum was used by the South American Indians before the fifteenth century. They could not melt it, but developed a technique for sintering it with gold on charcoal, to produce artefacts. A pre-Columbian Platinum ingot was found which contained 85% pure Platinum.
When the Spanish conquered South America, they discovered the Indians use of Platinum, and called it "platina", a diminutive which means "little silver", a somewhat derogatory term. It was considered by the Spanish as a worthless nuisance and impurity.
Platinum is closely related to five other metals, palladium, ruthenium, rhodium, osmium, and iridium. Together these six are known as the Platinum group metals, often referred to as PGM. They all have somewhat similar chemical and mechanical properties.
In about 1780, Janety was able to refine it using aqua regia, Smith & Tennant developed an arsenic refining method after 1800. This was highly toxic and dangerous.
Until about 1800, it was not realised that there were in fact six different metals. Platinum was not separated and identified until 1803.
Platinum's melting point is very high, and consequently it is difficult to melt. It was first melted by Lavoisier shortly after 1800.

Until large deposits were discovered by Merensky at Rustenberg in South Africa in 1924, 93% of the world's supply of Platinum came from the USSR. the Rustenberg deposits are considered very rich in Platinum. The ratio between Palladium and palladium recovered is 2.5%!

Platinum started to be used in jewellery in Europe about the mid nineteenth century, but it was not until the 1924 find that it started to become commonly used. It became very fashionable during the art deco movement.
It possesses very good mechanical properties for jewellery, being strong, and highly durable. It is ideal for stone settings as it has a low "spring-back" rate.
In jewellery, like other precious metals it is mixed with other metals to form alloys. Before 1975 there was no requirement for Platinum to be assayed and hallmarked in Britain, therefore there was no recognised standard. Because of this, most early pieces marked "plat" or Platinum, may be of very variable, and quite low fineness, and most would fail modern assay standards.
Platinum has been hallmarkable in Britain since January 1st 1975. From then until January 1st 1999, the only officially recognised standard of purity or "fineness" in Britain was 950 parts per 1000. From this year, there are now four standards, which are:-
850
900
950
999
parts per thousand.
Typically Platinum is alloyed with copper, iridium, palladium, rhodium, osmium or titanium.

Platinum has often been described as the purest, or the most precious metal. Both these claims are inaccurate. The "purest" claim was based on the fact that the highest purity precious metal generally recognised is sterling silver, at 925 parts per thousand (22 carat gold is 916 parts per thousand), but this ignores the fact that Britannia silver, 958 parts per thousand, has been a recognised standard in Britain since 1796.
The price of pure Platinum is generally higher than gold, but not always, therefore the claim that Platinum is the most precious metal is also a typical marketing exaggeration, besides rhodium is frequently double the price of Platinum. As noted previously, the Spanish conquerors of Latin America considered it a worthless nuisance.

Because of the high melting point, and the other difficulties in extraction and refining, Platinum is expensive to buy and process. This includes higher labour costs for manufacturing it, and also higher expense in recycling it. We can supply any of our own designs in Platinum on request.

Platinum was first used for coins in Russia 1828. In 1865 some Spanish gold coins were counterfeited using gold plated Platinum. In 1907 Louis Cartier made the first Platinum watch.
By the way, we frequently hear people, usually ones who think they know what they are talking about, calling it "Platignum", which is a brand name of pen.