Reading's Jacobs, independent jewellers' gemstones - natural, synthetic + laboratory.

Reading's Jacobs, independent jewellers' gemstones - natural, synthetic + laboratory.

Gemstones in Reading: natural or synthetic?

Unless expressly stated, all Jacobs gemstones (for example diamonds, rubies, emeralds, sapphires and more) are natural. The only artificial gemstones we offer are laboratory grown diamonds. Our natural coloured gemstones will all have had some form of treatment. Untreated natural coloured gemstones will be specifically referenced. 

What does this mean? The following excerpts from the National Association of Jewellers Guidance Notes explains more:


Natural inorganic or organic materials are used in jewellery or objets d’art due to a combination of properties that provide them with beauty, rarity, and relative durability.

Gemstones encompass:

  • -  Minerals; e.g. aquamarine, diamond, emerald, garnet, opal, sapphire.

  • -  Natural glasses; e.g. obsidian.

  • -  Rocks; e.g. lapis lazuli, opal with matrix and turquoise with azurite and malachite.

  • -  Organic gem materials; e.g. amber and jet.
    - Biogenic gem materials; e.g. pearl, coral and tortoise shell.

Artificial Products

Products which include a variety of materials that are partially or completely made by man.

Artificial Products with gemstone components

These are composite stones, examples of which include garnet topped doublets, opal on onyx doublets, soudè stones, which are beryl cemented with coloured cement, natural sapphire on synthetic ruby doublets, as well as ruby-glass composites, pressed amber and emerald on emerald doublets. These are all referred to as artificial products.

Artificially Crystallised Products with no known natural counterpart

Artificially crystallised products with no known natural counterpart include, e.g. yttrium aluminium garnet (YAG) and gadolinium gallium garnet (GGG).

Artificial Uncrystallised Products

Artificial uncrystallised products include man-made glass lead glass, plastic and products of various compositions, such as pressed materials (e.g. pressed turquoise) that are used to imitate the appearance of gemstones and organic gem materials.


This stands for High Pressure, High Temperature and is one of the primary methods used to grow synthetic diamonds in a laboratory. It can also be used to treat natural and synthetic diamonds to enhance their colour.

Synthetic stones

Synthetic stones encompass materials defined as man- made/artificial gemstones that are chemically and structurally identical to a natural gemstone rather than just a similar appearance. Commercially available examples include synthetic ruby, synthetic sapphire, synthetic emerald, synthetic amethyst and synthetic diamond (often referred to as Laboratory Grown Diamond).

Treated Gemstones

Treated gemstones encompass all gemstones/materials that have been subjected to a treatment. 

It is common for natural products to undergo processes to enhance their beauty and durability. Wood is usually impregnated and varnished, leather and fabrics are commonly dyed and coated, and gemstones are no different. These things help us to get the most value and enjoyment out of raw natural materials, give more choices, and allow us to use more of our precious natural resources.

Coloured gemstones are subjected to a growing range of treatments designed to enhance their value. For instance, heat treatment has been used to improve the colours in rubies and sapphires for around two thousand years and is a routine treatment on most rubies and sapphires in the market. Modern treatments can also diffuse chemical elements into some gemstones at high heat to radically change their colour. Irradiation is commonly used to enhance the colour of gemstones such as topaz, smoky quartz and fancy diamonds. Generally, these treatments are permanent and stable, which means they will not degrade or alter over time or with general wear.

The appearance of surface cavities, fractures, fissures and laser drill holes in gemstones can be minimised by filling them with glass, glass-like substances, oils and resins, and some porous or brittle gemstones can be impregnated with other materials. Such treatments can sometimes give added durability to the stone as well as improve the appearance. For instance, emeralds are routinely treated with oils and resins to provide a clearer appearance to the stone and are often referred to as “oiled” or “filled”. Many gemstones can also be dyed or coated to change or improve the colour. Jadeite and topaz are examples of such gemstones. If a gemstone has been identified as having been treated in any of these ways, then care must be taken in the maintenance, repair, cleaning, and often wearing or storing of the jewellery that contains it. Extremes of heat, steam and ultrasonic cleaning are not recommended; detergents, other chemicals, and potentially everyday wear may affect the treatment and, therefore, the gemstone’s appearance.


If you'd like to know more, or would like us to help you with an enquiry, do make contact.

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Article by Adam J

Adam J

Adam looks after the business as a whole and been working at Jacobs since 2003. He has a professional jewellers diploma from the National Association of Jewellers and a BSC Honours in Business Administration.

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