Guidelines for Purchasing: Understanding Hardstones
In the world of art and jewellery, the term 'hardstone' has been a traditional catch-all term, referring to semi-precious gemstones that are durable and often opaque or translucent. However, as the jewellery trade and decorative arts evolve, there is a growing movement to replace the term 'hardstones' with alternatives such as 'ornamental stones' or 'artisanal stones'.
Originally, the Romans favoured carved gems like cameos and intaglios made from 'hardstones' such as agate, jasper, garnet, and carnelian. Fast forward to modern times, and the list of hardstones has expanded to include a variety of semi-precious stones, such as lapis lazuli, malachite, turquoise, and agates.
Lapis Lazuli, known for its deep blue color and often with gold or white calcite inclusions, is one of the most commonly cited hardstones. Malachite, recognized for its striking green banding, is another popular hardstone, despite its hardness of 3 to 4, which is lower than that of quartz. Turquoise, with its blue-green hue and historical significance, is another stone that falls under the hardstone category.
Jasper, available in a wide range of colors and patterns, and sodalite, deep blue with white veins, are also considered hardstones. Onyx, black or banded black and white, and agate, highly banded and available in many colors, are common hardstones used for carving. Carnelian, translucent orange to reddish-brown, and tiger's eye, an ornamental stone with a silky chatoyant effect, are also included in the list of hardstones.
Coral, an organic material, is historically included due to its use in carving and jewellery. Rhodonite, bloodstone (heliotrope), jade (nephrite or jadeite), and obsidian are sometimes grouped with hardstones, though they can sometimes be categorised with other decorative or semi-precious stones.
Hardness in gemmology is gauged by observing what materials a stone will scratch and what it will be scratched by. Diamonds, rubies, sapphires, and emeralds, which are harder than hardstones, are not typically called 'hardstones'.
In contemporary high jewelry collections, hardstones are often used as a complement to more expensive gemstones. Brands like Chanel, Garrard, Dior, Pomellato, Cartier, and Veschetti have incorporated hardstones into their collections. The term 'hardstone' is also used to describe carvings or table ornaments in an auction house context.
However, it is important to note that hardness is not the same as 'toughness'. For example, quartz, a common hardstone, might only split in two. A diamond, the hardest gemstone on the Mohs Scale, is brittle and will shatter if hit with a hammer.
Identifying all the stones used in hardstone inlay can be challenging due to their sizes and accessibility. The techniques of hardstone inlay were developed in Italy and India in the 16th century and are still practiced today.
The term "semi-precious" is often misleading when referring to hardstones, as prices for them may be high after they have been worked. A jewelled breastplate from the tomb of Tutankhamun in Egypt is a testament to this, as it is set with a glass scarab which is thought to have formed as a result of a meteorite striking Earth.
Some of these materials have been used for thousands of years, such as quartz gems and lapis lazuli. As the jewellery trade and decorative arts continue to evolve, it will be interesting to see how the concept of hardstones evolves with it.
In the realm of gemmology and jewelry, hardstones like lapis lazuli, malachite, and turquoise, which were once favored by the Romans, now find a place alongside fashion-and-beauty items and home-and-garden decor. These stones, such as agates and jaspers, are often used in education-and-self-development courses focusing on gemology. As contemporary high jewelry collections continue to expand, brands like Chanel, Dior, and Cartier incorporate hardstones alongside more precious gems. However, it's crucial to understand that hardness in gemmology is different from toughness, as demonstrated by the brittle nature of diamonds, despite them being the hardest gemstone on the Mohs Scale.
