Getting to Know Gold

Gold is a valuable metal which is why it holds generational value in jewellery and is often referred to as 'heirloom' jewellery.

‘Gold's lustrous and metallic qualities, its relative scarcity, and the difficulty of extraction have only added to the perception of gold as a valuable commodity’ (source).

Solid gold jewellery is an investment that you will be able to enjoy for life, even generations, so before you make a purchase it is worthwhile to inform yourself about the different options of gold available and what official markings to look for in your investment pieces.

 By Leahy Makers Mark, 18ct Gold Hallmark, and the Irish Assay Office hallmarks.


The weight of gold is measured in troy ounces (1 troy ounce = 31.1034768 grams), however its purity is measured in ‘carats’. The word carats is believed to have come from ‘Caratage’ which is the measurement of purity of gold alloyed with other metals. The word 'karat' is a variant of the word 'carat'. In Ireland and the UK, the symbol ct (carat) is used while in the US it is kt (karat), as confirmed by the Irish Assay Office. Confusingly, the term 'carat' is also used in reference to diamonds and may be why we sometimes see kt used in relation to gold on this side of the Atlantic.

24ct is pure gold with no other metals. Lower carats contain less gold; 18ct gold contains 75 per cent gold and 25 per cent other metals, often copper or silver. 9ct gold contains 37.5 per cent gold and 62.5 per cent other metals, often copper and silver. To read more on the technical side of gold from the World Gold Council, follow this link.

The Company of Goldsmiths of Dublin governs the Assay Office, located on the grounds of Dublin Castle, Ireland. According to their records the Company was established and incorporated by royal charter of Charles I on 22nd December 1637. 

The Company is responsible for enforcing 'minimum standards of fineness for the quality of gold, silver and platinum to be used in manufacture and the submission to the Company of all gold, silver and platinum wares for assay and hallmarking' (source). Fineness is another way of expressing the precious metal content of gold jewellery and represents the purity in parts per thousand. For example, .750 = 18 carat gold and .375 = 9 carat gold.

As mentioned above, most items of precious metal, referring to gold, silver and platinum, are not made from pure metal. In a retail environment it is not easily possible for you, as the consumer, to know if the correct percentage of precious metal is present in the article or not, unless the item is hallmarked. This is where the importance of the hallmark comes in – it guarantees and indicates the precious metal content.

"Irish hallmarks provide the final consumer with a unique guarantee of the precious metal content that lasts the lifetime of the product." (source)

The marks stamped were known as 'Hallmarks', because they were stamped in Goldsmiths Hall – the original and current meeting place of the Company. The Company laboratories are one of the leading precious metal test laboratories in the world. Fundamentally, the original purpose – to protect the public from fraud when buying gold, silver and platinum – still remains.

 By Leahy Fine Jewellery Certificate of Registration, Company of Goldsmiths of Dublin, Assay Office Dublin Castle
By Leahy Fine Jewellery Certificate of Registration, Company of Goldsmiths of Dublin, Assay Office Dublin Castle 


Every item of By Leahy Fine Jewellery is stamped with the official seal of approval – the hallmark guarantees the purity and quality of the precious metal so that you are reassured that when you buy an 18ct gold, 9ct gold, or sterling silver piece from By Leahy, that is exactly what you are getting. Read more about the hallmarking process in the blog 'The Final Seal of Approval - The Irish Assay Office'.

If you have any questions about By Leahy jewellery, don't hesitate to contact Laoise on hello@byleahy.com or DM on Instagram.

In the meantime, I'll leave you with some fun facts about gold:

  • All By Leahy gold pieces are made from 100% recycled gold.
  • One ounce of gold can be beaten into a translucent sheet 0.000018 cm thick and covering 9 square metres; or pulled into a wire 80 km long.
  • Over 90 per cent of the world’s gold has been mined since the California Gold Rush.
  • The largest gold coin ever created was cast by the Perth Mint in 2012. Weighing one tonne and measuring 80 cm in diameter, it surpassed the previous record, a 2007, C$1 million coin which was just 53 cm across.
  • Virtually indestructible and endlessly recyclable, all of the gold that has ever been mined is still with us today – almost 200,000 tonnes. Watch this short animated video of the gold supply chain.