Often customers ask the question, what is the difference between 9k and 18k gold? What are the benefits of 18k gold compared to 9k? There's generally a misconception that 9k is more durable, but this is not always the case. Here we will quickly run through the pros and cons of each alloy.

What Are Karats?

Karats, or carats, refer to the pure gold content in gold alloys, and is a measurement of the ratio of gold to other metals in the alloy. Other metals in alloys can include copper, silver and palladium, with small amounts of zinc and iridium.

Gold is a rather soft metal, which is why it's alloyed with other metals to make it harder. However, in normal life applications, 18k gold is perfectly durable due to other metals present in the alloy.

9k vs 18k gold

Lower karat gold, such as 9k, is not tarnish-resistant but can be easily polished with a jewellery polishing cloth and look like new again.

Obviously, the higher the pure gold content, the higher the cost - the price difference between 9k and 18k pieces is usually around 60%. Generally, we recommend using 18k gold for important pieces such as engagement or wedding rings, or special jewellery set with precious gems.

9k gold is composed of 37.5% pure gold hence the gold mark 375 then alloyed with other metals to produce the desired colour. As there is a smaller gold component and a greater component of other alloys, the metal is less durable than 18k gold. It will tarnish and corrode more easily, especially when exposed to the wearer's skin acids over time. However, because of the lower gold content, 9k gold is a lot more affordable. It's perfect for more casual jewellery pieces and dress rings with large semi-precious gem stones or earrings that have less contact with the wearer's skin.

18k gold is composed of 75% pure gold and is stamped 750. Because pure gold has more tenacity and flexibility than the other metals it is mixed with, and as it's the dominant component, this alloy is more durable and is unlikely to corrode and tarnish with normal wear. 18k gold is perfect for wedding and engagement rings and jewellery pieces that are to be worn every day. It's our preferred metal for setting precious gems such as diamonds, rubies, emeralds or sapphires, and other valuable gems like spinels, tourmalines, opals and alexandrite. It's the more expensive choice, however highly worthwhile for fine jewellery pieces.

In Australia, we typically make jewellery in 9k, 14k or 18k gold. 22k and 24k yellow gold is also used in jewellery, with 24k being 100% pure gold.

Precious emeralds have been used in bespoke jewellery for centuries. Emerald is part of “top 3” coloured gemstone suite, along with ruby and sapphire. These highly coveted gems are prized for their beauty, exceptional colour and fascinating historical provenance.

Emerald, Be₃Al₂(SiO₃)₆, is the most precious green coloured gemstone and a member of the beryl gem family, whose members also include aquamarine, morganite, heliodor and goshenite. Trace amounts of chromium and vanadium give emerald its beautiful green colour. Emeralds have been a firm favourite for exquisite bespoke jewellery pieces worn by royalty and stars throughout history.

Emeralds have for centuries been strongly associated with power, beauty and fame, and were the preferred gemstone of many of history’s most beautiful and powerful women. Cleopatra was famous for her love of the verdant gems. The Egyptians were perhaps the first civilisation to mine emeralds in Upper Egypt near the Red Sea, as far back as 3500 BC. With the discovery of the Colombian deposits by the Conquistadors during the 1500s (the indigenous Indians had been mining the Muzo emeralds as early as 500 AD) the superb quality gems became the rage with European courts. The infamous “Isabella Emerald” – a 964 carat emerald crystal – was in the end presented to the future wife of Hernan Cortez in exchange for a large dowry which funded his future voyages. Queen Isabella of Spain was furious that it wasn’t presented to her and always coveted the mystical gem.

Screen goddess Elizabeth Taylor had a tremendous passion for exotic gems and Richard Burton presented her with the iconic Bvlgari emerald and diamond necklace as a wedding gift in 1964 (as well as other treasures during the 1960s and 70s). Contemporary actress Julianne Moore had the honour to be the first person to wear the necklace after Ms Taylor in 2013. Superstar Angelina Jolie made headlines wearing large emerald earrings to the Oscars in 2009.

EMERALD COLOUR

Emeralds of medium to dark tone with strong saturation and bright, vivid green colour are the most valuable. Green is the primary hue in emeralds, with yellow and blue the usual secondary hues.

DURABILITY

Emerald is reasonably hard and measures 7.5 on the Mohs hardness scale. As most material is highly included, emerald is a brittle stone and care must be taken when wearing emerald jewellery, especially in ring settings. Emeralds can’t withstand the vibrations of ultrasonic jewellery cleaners so should be gently cleaned in warm water with a dash of mild liquid detergent, with a soft brush to eliminate scratching the setting.

VALUE

Emeralds are 20 times rarer than diamonds and their per carat price can be four times as great. Emeralds with no visible inclusions are valued more than the more included material. Internal inclusions in emeralds are called “jardin,” French for "garden" due to their mossy appearance.

Emerald has lower density than other gemstones and an emerald weighing 1 carat is larger in physical size than a 1 carat diamond.

SOURCES

The first known emerald mines were in Egypt, believed to be worked as early as 3500 BC. Traditionally Colombian emeralds are the most prized on the contemporary market, and Colombia is by far the largest producer, with three main mining areas being Muzo, Coscuez, and Chivor. Due to a natural phenomenon, the gems are produced hydrothermally due to huge surges in heat and pressure when two different rock types come together. They are coloured by chromium and vanadium and have the most gorgeous rich silky green colour.

In the 1920s a significant emerald deposit was discovered in Zambia, however mining didn’t become established until the 1970s. Many of the major jewellery houses now use the Zambian material. Generally the African material has more of a blue undertone (due to lower vanadium content) and the stones are generally less included than their South American cousins. Zambia is now the world's second largest producer of emeralds.

Even Australia is blessed with our own emerald deposit in Torrington, NSW. These very rare gems are unique, often with green and clear banding and truly are collector’s items. The deposit has long been exhausted which makes these stones even more covetable.

Emeralds are also found in Afghanistan, Austria, Brazil, Cambodia, Canada, China, Ethiopia, India, Italy, Kazakhstan, France, Bulgaria, South Africa, United States, Tanzania and Russia, among others.

TREATMENTS

The majority of emeralds on the market today is treated by a process called oiling to improve clarity and stability. This is a widely adopted and accepted practice. Oils with a similar refractive index to the emerald are used, and are applied post cutting in a vacuum chamber under mild heat.

SYNTHETICS

Synthetic emeralds have been produced since the 1960s, using both the hydrothermal and flux-growth techniques. The chemical and gemological composition of synthetic emeralds is identical to natural emeralds, and they are widely used in jewellery. While synthetic emeralds are difficult and expensive to produce, they are nowhere near as valuable as natural, mined emeralds.

EMERALD SPECIFICATIONS

Hardness: 7.5-8 Mohs

Specific Gravity: Average 2.76

Refractive Index: N_ω = 1.564–1.595, N_ε = 1.568–1.602

Crystal Form: Hexagonal (6/m 2/m 2/m)

Treatments: Oil

Durability: Brittle, should be worn with care

Image: Bespoke Emerald, Sapphire And Diamond Ring By Lizunova Fine Jewels

Sapphire is a precious gemstone and part of the most important gem family - corundum, which also includes ruby. Both sapphire and ruby have been used in important jewellery, such as imperial crowns, for centuries, and have consistently risen in value and popularity, due to their rarity, beauty, durability and versatility. They have the same chemical composition and structure, with presence of certain metals determining their colour. Corundum is also known for its high density, unusual for a transparent mineral.

Sapphire has become the centre stone of choice for contemporary engagement rings due to its durability, beauty and incredible variety of colour. It works exceptionally well in a multitude of ring designs, from the simple and timeless solitaire, to trilogy, or three stone ring design, to the more intricate diamond halo designs, or unique, asymmetric ring designs.

Here we look at the colours, value, durability and other characteristics of this gorgeous gem.

Sapphire Colours

Sapphire is the most precious blue gemstone, and blue is this gem's most well known colour. But they naturally occur in a rainbow of colours beside various shades of blue: teal, black, white, grey, orange, pink, green, purple, yellow and the rare and extremely valuable Padparadscha (pinkish orange).

Bi-colour or parti sapphires (stones with two colours in the same crystal, eg yellow and blue) occur in Australia as well as Africa (Madagascar, Tanzania and Nigeria).

All sapphires are made of the same elements, aluminium oxide (α-Al₂O₃) but the trace elements present in the growing process, such as such as iron, titanium, chromium, vanadium, nickel and magnesium, give each stone its unique colours.

Sapphire Durability

Corundum family is the hardest, most durable natural gemstone after diamond and measures 9 on the Mohs hardness scale, making it a popular choice for jewellery worn every day, such as engagement rings. Despite their durability, they should be protected like any other precious stone, and sapphire jewellery should be removed before engaging in heavy work, such as gardening or construction, or work that would expose them to harsh chemicals.

Value

Sapphires have for centuries been associated with wealth and royalty. They are valuable gems, especially larger stones, but those of high colour saturation and particular shades of blue - royal blue and cornflower blue), as well as pinkish orange (Padparadscha) are particularly prized. Blue sapphires are valued for the purity of the blue hue, without secondary hues of purple or green. Blue sapphires of vivid saturation and pure blue hue command the highest prices. Vivid pink sapphires, their colour and saturation determined by the quantity of chromium, are also highly prized. Red corundum is called ruby, less saturated stones are classified as pink sapphires.

Sources of Sapphire

Sri Lanka produces many beautiful sapphires of gem quality. Blue sapphires from Kashmir and Sri Lanka are among the most valuable. Other sources of sapphire include Africa (Tanzania, Nigeria, Madagascar, Kenya, Malawi), Brazil, Myanmar (Burma), Thailand, Vietnam and United States (Montana). Many of the unique parti and green sapphires hail from Australia (Queensland and New South Wales).

Treatments

Heating is a common treatment that lightens or intensifies colour, improves uniformity and enhances clarity. A sapphire is gently heated in a kiln to remove or dissolve any silky rutile inclusions back into the matrix of the stone. Heating does not damage the gem and is a lasting treatment that does not wear off with time.

Synthetics

Corundum has been synthesised since the beginning of the 20th century. Synthetic sapphire is mostly used in many industrial applications, such as scratch resistant glass, semiconducting circuits and lasers. Synthetic corundum can be recognised under magnification by the curved growth lines following the top surface of the rough crystal. Natural corundum crystals have angular growth lines expanding from a single point and following the planar crystal faces.

Specifications

Hardness: 9 Mohs

Specific Gravity: 3.95-4.03

Refractive Index: 1.760-1.774

Crystal Form: Trigonal. Crystals occur as barrel-shaped, double-pointed hexagonal pyramids and tabloid shapes. Corundum is found in igneous and metamorphic rocks and also in alluvial deposits.

Treatments: Heating

Special Care: None

Durability: Very good

Sapphire in jewellery

Sapphires have been highly prized and used in important jewellery for centuries - from royal crowns to famous engagement rings, such as Princess Diana's sapphire and diamond halo ring, now belonging to Kate Middleton. Due to its exceptional versatility and durability, sapphire is beloved by modern couples as the engagement ring centre stone of choice, and it allows unparalleled self expression in ring design. We love working with this beautiful gem and have a collection of handpicked loose sapphires from Australia, Sri Lanka and Africa to create the perfect engagement ring to cherish forever. We work with customers all over the world and ship internationally. In person and online appointments are available - book your complimentary bespoke engagement ring design appointment or email us with any questions. We look forward to working with you on creating your dream ring!

Image: Parti Sapphire Engagement Ring By Lizunova Fine Jewels