Teal Sapphire & Diamond Ava XV Ring

With a distinct Scandinavian aesthetic and enduring fascination for geometry, Kamilla Ruberg draws inspiration from her creative home, architecture and sculpture. It is asymmetry however, which remains the signature trademark of Ruberg fine jewellery.

Most commonly found in shades of blue, sapphires are also available in pretty much every other colour you can think of, with pink, yellow, peach and green being the most popular after blue. Sapphires are also very hard, with their rating on the Moh’s Scale falling just under diamonds, so they make great gemstones for daily wear on the hand.

The quality and therefore price of sapphires is based on their colour, cut and clarity, and large stones can be GIA certified as diamonds are.

The colour of the sapphire is by far the most important of all these. The shade, the tone and the depth of colour, as well as the uniformity of the colour - how well the shade is spread over the stone evenly - make a huge difference to price. Deep, dark coloured tend to hide the sparkle of the stone, so become less desirable, and sapphires that show a pure, even colour and brightness will be more expensive.

You may see sapphires where there are two different shades of colour in the stone. This is called a bi-colour sapphire, and is very common. Pure coloured sapphires with a rich, even tone in a single hue are the most conventionally desirable varieties, and therefore the most expensive. Common ‘cheaper’ sapphire rings found online will often feature lesser quality gemstones and the images may have been digitally altered, so make sure you always see a coloured gemstone in real life before buying.

Depending on the size requirements sapphires make a beautiful alternative to coloured diamonds. Yellow sapphires, white diamonds and yellow gold are currently a popular choice, but our favourite sapphire shade is a murky olive green.

Sapphires are traditionally the birthstone of September. See all Sapphire rings here.

Like the round diamond's sexier sister, the oval cut diamond is longer and slimmer than a classic round shape. But be cautious: the oval diamond can take various shapes and forms depending on the height to width ratio, and whereas it's a personal choice, the proportions are important to make sure the sparkle is maximised. For this reason you'll find that prices vary a lot even if the carat weight is the same, as more 'desirable' ratios will be more expensive.

The oval diamond is our choice for a solitaire engagement ring; more unexpected than a round diamond, and the longer height elongates the fingers.

See all oval cut diamond rings here.

The sapphire in the image is 1.56ct and the baguette cut diamonds are 0.20ct and 0.11ct.

Ring Size M 1/2

Gold is a naturally occurring metal with a warm, glowing finish when polished, and remains the most popular choice for engagement rings due to its natural beauty and hard-wearing strength.

Pure 24k gold is naturally a soft material, and considered too soft to create jewellery with, so it is mixed with small amounts of other metals to create an alloy.

As well as increasing the durability of the gold, adding alloys can also change the colour of the gold to produce rose or white gold, for example.

18k yellow gold is made up of 75% pure gold, and 25% alloy, which would usually include silver and copper.

18k rose gold is made up of 75% pure gold, 22.2% copper, and 9.2% silver.

18k white gold is made up of 75% pure gold and 25% palladium or platinum.