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What Is 18ct Gold?

Not all gold jewellery is created equal. 18ct Plated, Filled, Vermeil or Solid Gold – would you know the difference? Find out what sets 18ct Solid Gold apart from the rest. 

There’s nothing quite like 18ct Solid Gold. It’s the epitome of luxury and class. With its timeless beauty and numerous benefits, it’s easy to see why this precious metal is a popular choice for jewellery. At Auric Jewellery, we often get asked if our fine 18ct Solid Gold Jewellery pieces are real - we can assure you they are. The clue is in our name, ‘Auric’, which means ‘derived from gold’. With all the different names for 18ct gold jewellery like Plated, Filled, Vermeil and Solid, it’s understandable how easy it is to get confused by the terminology.

So, that you can focus on finding the perfect Auric piece for your style, we will break down all you need to know about the differences in gold jewellery for you.


What is Solid Gold & How Do You Measure its Purity?

Let’s start by taking a moment to define what solid gold is. Solid Gold is a naturally occurring, rare precious metal found in its pure form in the earth. It has been used for centuries as a form of currency, jewellery and other decorative items.

Gold in its purest form is referred to as pure gold, fine gold, or solid gold. There are two systems for measuring the purity of gold in jewellery: the carat system and the millesimal fineness system.

The carat system represents the purity of gold by fractions of 24 (pure gold is referred to as 24 carat). Therefore, 18ct gold is 18 parts per 24 or 75% pure gold. The higher the carat (ct) in your gold jewellery, the purer and more valuable your jewellery piece is.

The millesimal fineness system represents the purity of gold by parts per thousand. Therefore, 18ct solid gold jewellery containing 75% gold is shown as ‘750/1000’. This system is used when hallmarking precious metals.

Pure gold is 24 Carat (24ct), or it is 99.99% pure in percentage terms. Auric Jewellery is committed to being environmentally conscious. All our jewellery is sustainably and ethically produced from recycled gold to create fine 18ct Solid Gold collections that you can feel good about wearing. 


What’s the Difference Between 24ct Solid Gold and 18ct Solid Gold?

Pure solid gold (24ct) is too soft to use to make jewellery as it deforms easily. For this reason, pure solid gold is alloyed with other base metals, such as silver, platinum or copper, to alter its hardness, durability and appearance.

One of the most popular choices for jewellery is 18ct Solid Gold. For 18ct Solid Gold jewellery, 75% of the jewellery piece is comprised of pure solid gold, which gives it a rich yellow colour, hence the name ‘Yellow Gold’. 18ct gold is not only beautiful, but it is also strong and durable. It does not tarnish, corrode or react with your skin. Pure Gold = 24 Carat = 99.99% Pure. 


18ct Solid Gold: The Breakdown

18ct Solid Gold jewellery comprises 18/24 parts pure gold, meaning it is 75% pure gold. The other 6 parts (25%) are a combination of metals like silver, platinum and copper, which give the jewellery its strength and colour.

75% pure solid gold (18 parts of pure solid gold) + 25% of other alloys such as silver,platinum or copper or (6 parts of silver, platinum or copper) = 100% 18ct Solid Gold Jewellery.

How Is 18ct Solid Gold's Fineness Authenticated?

In the UK, Gold jewellery which is 1g or over, must have an Assay Office Hallmark Stamp. The hallmark from one of the Assay Offices assures and certifies purity of the gold in the jewellery as this is independently verified.

The hallmark engraving stamp consists of three marks:

The first type of mark is called a makers or sponsor mark. This mark identifies the company or business who is submitting the jewellery piece for hallmarking. For Auric Jewellery, this mark is represented by the letters AU enclosed in a diamond.

The second is a purity mark. This mark shows the carat or purity of the jewellery piece. For 18ct solid gold jewellery, this is represented by the number 750, annotated for 75% pure gold.

Lastly, the third mark is the Assay Office mark. This mark shows the stamp of the Assay Office, which has validated the jewellery’s purity. Most of Auric Jewellery pieces are hallmarked in Birmingham. This is represented by the Birmingham Assay Office Anchor Symbol.


18ct Solid Gold Hallmark Stamp

What Is The Difference Between 18ct Solid Gold, Gold Filled, Plated And Vermeil?

It’s important not to confuse 18ct Gold Filled, Plated and Vermeil jewellery with 18ct Solid Gold jewellery. Even though they may look like solid gold, they are entirely different and don’t hold the same value or longevity as 18ct Solid Gold Jewellery.

Let’s summarise the primary differences below:

Solid Gold Jewellery Fine solid gold and other precious metals are mixed to create an alloy which is stronger and longer lasting. 18ct Solid gold jewellery is 18 parts of real gold and 6 parts other metals such as silver, platinum or copper. Solid Gold jewellery is more durable than gold Filled, Plated or Vermeil jewellery. It will not tarnish or change colour over time, which is why, at Auric Jewellery, our entire jewellery collection is crafted in 18ct Solid Gold.

Gold Filled jewellery is made using a mechanical bonding process that melts a thin layer of gold onto the thicker base metal, usually brass or copper. By law, gold-filled jewellery must only contain 5% gold by weight. The gold content is only 5%, so the value of the gold-filled jewellery is very low.

Gold Plated jewellery is made when a base metal such as brass or copper is rapidly dipped in gold. The gold percentage on the resulting jewellery piece will be less than 1%. Gold-plated jewellery is most likely to fade in colour or peel off over time and does not retain any value.

18ct Gold Vermeil jewellery (pronounced ‘ver-may’) is like gold plating; however, the base metal is silver rather than brass or copper. The gold layer on the jewellery piece is slightly thinner (2.5 microns of gold). 2.5 microns or 0.00025mm of gold is equivalent to the thickness of a single strand of hair. This type of jewellery is hallmarked as silver jewellery ‘925’, rather than solid gold jewellery (its gold content is not worth anything). Over time the thin layer of gold will wear off, and the silver underneath will start to show through.


The Benefits Of 18ct Solid Gold Jewellery

18ct Solid Gold is an investment in yourself. Jewellery in 18ct Solid Gold is made to last, not tarnish or irritate the skin. It also doesn’t fade colour like lower-carat gold or plated may do over time. This makes 18ct Solid Gold ideal for lifelong jewellery pieces.

With this new information about the differences between 18ct Solid Gold and 18ct Filled, Plated, and Vermeil jewellery, take some time to explore our fine collection. Then, choose your next favourite piece to add to your fine jewellery collection.