With some 300 varieties of gemstones available, the wonderful world of gemstone jewellery is a celebration of colour, beauty and uniqueness.
As you’ll discover when exploring the many different gemstones, however, not all were created equal. Gemstones are categorised into types as a result, with precious, semi-precious, soft porous and treated gems having their own characteristics and jewellery care rules. But what’s the difference between these gemstone types?
Out of the 300 gemstone varieties identified, only four are classed as precious. Known as the ‘Big Four’, diamonds, emeralds, sapphires and rubies are precious gemstones and are generally considered the most valuable and expensive. This is a misconception, however.
Despite their precious status, precious gemstones aren’t always the rarest or most valuable as Bellatory details:
“All gemstones are rare to some degree. Whether it be Tanzanite from Africa or Rubies from Sri Lanka. The special circumstances that are required to create a gemstone, pressures, heat, and combinations of unique minerals, all come together to form a gem or gemstone. When we look, however, at how rare one gemstone is compared to another, there are many gemstones that are much rarer than the gemstones that are known as the ‘Big Four’…”
One thing that precious gemstones do have in common is their hardness. Diamonds, emeralds, sapphires and rubies all top the Mohs scale when measuring mineral hardness, making them durable, easy to care for, and able to last for generations.
Outside the Big Four, gemstones are classified as semi-precious, and there is a lot to love about this particular gem type. As well as often being better quality and more valuable than some precious stones, semi-precious gems deliver exquisite colour, brilliance and beauty.
Semi-precious stones include alexandrite, amethyst, aquamarine, topaz, garnet, peridot and rose quartz.
Due to their varying hardness, some semi-precious stones need more specialist care and handling than others. Selected stones are particularly susceptible to damage when exposed to excessive heat, light or chemicals.
Whilst most precious and semi-precious gemstones are hard and non-porous. A select few fall into the soft porous category. Pearl, opal, emerald, amber, coral, onyx, agate and dolomite are all classed as soft porous, which means they are softer, more vulnerable to water damage and need special care to maintain their beauty.
With this, most soft porous gems shouldn’t be cleaned with, submerged in or exposed to any water at all to avoid stone discolouration or damage. Instead, a dry, soft jewellery cloth should be used for cleaning.
As the name suggests, treated gemstones have undergone some type of treatment to achieve their final colour and/or quality.
Howlite and lapis are categorised as treated stones, with dye, oil, wax or heat used to shape the looks and qualities they are known and loved for. Despite their treated nature, they need just as much of a specialist touch as soft porous stones when cleaning and handling.
Like soft porous stones, treated stones should be kept away from water. Products containing alcohol also shouldn’t be used on treated stones, especially gems that have been dyed. The alcohol can cause colour transfer, dulling and discolouration.