Precious Stones and Metals
Gold is a “precious metal” – it is relatively scarce and very beautiful which makes it very valuable across history and the world today.
Gold is an element, a metal, with atomic number 79. It is very stable and doesn’t corrode or rust. Its chemical symbol is Au.
Pure gold is very soft, and not suitable for long lasting jewellery. The gold you traditionally buy in jewellery form today is a metal alloy. Gold is alloyed with other metals to make it harder, more durable and varying prices.
In New Zealand, gold jewellery is usually sold in either 9 or 18ct form. The lower the carat, the lower the gold content. This means more alloyed metals have been mixed with the gold for different reasons. This can be to make it stronger, or to change the colour such as in white and rose gold.
WHITE GOLD: White gold is still largely yellow gold, but is mixed with other metals to give it a white colour. These metals could be palladium, platinum or manganese. Sometimes copper, zinc or silver are added also. These added metals add strength and stability to the pure gold so it is suitable for jewellery. White gold can benefit from plating with rhodium every year or two. Rhodium is an extremely precious metal which gives a very dazzling white shine!
ROSE GOLD: Rose gold is a very subtle pinky/red hue of gold. This is where copper coloured alloys are added to the gold to create strength and colour. Rose gold is becoming increasingly popular, and can look extremely beautiful.
Rose and white gold has the same stamping as yellow gold, because the alloy quantities are the same.
Gold jewellery should always be stamped or hallmarked as follows:
Silver is one of the first metals used by humans. There is a lot of silver around, it is very common so its value isn’t as high as gold.
Silver is one of the leading metals used in jewellery because of its low price, and is popular among young people because it is affordable but still gives a beautiful formal look.
Silver can be polished to an extremely high finish! It can be so well polished and reflective in fact, that it’s chemical symbol ‘Ag’ means “white and shining” in Latin!
In its pure form, silver is almost as soft as gold, but it is usually alloyed with copper to make it stronger which is “sterling silver”
Sterling silver is 92.5% pure silver. Sterling jewellery should be stamped .925 inside for authenticity
Stainless steel is most commonly used for men’s jewellery, bracelets, cufflinks etc but is becoming more widely used for women’s jewellery as well.
Stainless steel is corrosion resistant, very strong, is easy to look after and care for and can be very nicely cleaned.
It has a similar appearance to silver, but is much harder and will not tarnish. It is made without nickel making it hypoallergenic for those with metal allergies.
Platinum is extremely precious. It has been widely used throughout history, but it is much rarer than gold.
It is a heavy metal and is incredibly hard and durable. It is highly dense which gives it great resistance to wear and tear. Platinum ring settings often last two to three times as long as white gold before they need any repair.
Platinum is the only metal used in fine jewellery that is 90 – 95% pure, hypoallergenic and tarnish resistant.
Platinum jewellery is marked with 950 or Plat.
Diamonds are of course the most commonly known precious stone, but coloured stones are still prized and loved for their different characteristics. Coloured stones are used to create unique, eye catching and valuable jewellery. Some of the most commonly used stones for precious jewellery are detailed below:
The mineral name for a Ruby is ‘Corundum’
Ruby is a bright red stone, but can include pinky, purply and orangey reds depending on where the stone was found.
Most commonly found in Burma and Thailand, rubies have been very popular throughout history.
The ruby can naturally be quite cloudy inside, so are often heat treated to clarify the colour inside.
Ruby is very hard and tough which makes it perfect for jewellery. Of course if a ruby has many inclusions and fractures it is less stable. For nice clear stones, no special wear or care is necessary but you do have to be wary of chipping and damage.
An emerald is very rare, even more so than a diamond.
Emeralds are highly prized and very valuable.
They are quite a brittle stone so require extra special care when being worn as jewellery. They contain natural inclusions which aren’t faults, but more like individual unique characteristics of a stone.
Sometimes they are fracture filled which is filling of surface breaks to reduce whitish looking inclusions.
They are a stunning green colour and make absolutely beautiful, valuable stones to use in jewellery.
Sapphires are also the mineral called ‘Corundum’.
Blue or pink Corundum is called sapphire or pink sapphire.
Sapphires have a very hard crystal structure making them ideal for jewellery.
They come in all range of colours from blue to black and white and pink.
Sapphires can be found in Madagascar and Sri Lanka, Thailand, Australia, Brazil and other countries.
Sapphires are most commonly cut in an oval shape, but can be cut in any shapes. You can sometimes found sapphires cut in a ‘cabochon’ shape which is flat on the bottom, and smooth and round on top.
Genuine sapphire is becoming increasingly expensive due to their rarity and properties and makes a great stone to invest in.
Tanzanite is a very special and unique stone.
It only comes from one part of the world – Tanzania in Africa.
Tanzanite is an extremely deep, magnificent blue colour but can range in colour to a light purplish blue. Sometimes tanzanite stones can give two colours within one stone. This is an amazing phenomenon. The most coveted colour is a blue which shows a purple hue shimmering around it.
It is extremely valuable due to its exclusive origin and its spectacular colour.
Citrine is a stunning orange or yellow stone.
It is very affordable because it is durable and readily available.
It is named for the French name for lemon or “citron.
It can be yellow to orange or brown.
Most citrine is mined in Brazil.
Topaz is a beautiful blue stone which comes in many shades.
Often it is heat treated to become blue. Clear topaz hasn’t got a lot of value, but they are treated with an “irradiated” treatment to bring out the colour.
Natural blue topaz is very rare, but it is easily created from a clear stone.
Pink topaz is also very rare. It is highly valued.
It is very hard and durable and can be cut into virtually any shape.