Parti sapphires

July 22, 2020

Australian-parti-sapphire-Sydney-jeweller-Lizunova-Fine-Jewels-Chifley-Square

Sapphire is part of the most important gem family, corundum, which also includes ruby. Both sapphire and ruby have consistently risen in value and popularity, due to their beauty, durability and versatility.

Sapphire colours

Sapphires naturally occur in a rainbow of colours: blue, teal, black, white (colourless), grey, orange, pink, green, purple and yellow. 

The colour in Australian green sapphire is typically made up of a mixture of yellow and blue coloured banding within the crystal mixing to produce the green colour. When some of these yellow and blue banded sapphire crystals are cut suitably, stones know as ‘parti’ (short for partition) can be created. 

Bi-colour or parti sapphires occur in Australia as well as Africa (Madagascar, Tanzania and Nigeria).

A parti sapphire is made of the same elements as other corundum (Al 20 3) but the trace elements present in the growing process give each stone its unique colours. Presence of iron gives parti sapphire its yellow colour, and blue comes from a mix of titanium and iron.

Australian sapphires are from alkali-basalt related deposits and are very rich in iron content. Due to varying concentrations of transition elements (e.g. iron and titanium) in the chemical make-up of the parent fluids (sapphire is essentially aluminium oxide), different colours result. The parti sapphires are so special as each stone has a unique combination of zoning and banding. The colour zoning seen in parti sapphires relates to the growth layers of a crystal, and appears as a series of concentric hexagons parallel to the prismatic crystal faces.

Durability of parti sapphires

Corundum family, which parti sapphire is a member of, is the hardest, most durable gemstone type 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.

Parti sapphire value

The rarity of parti sapphires makes them valuable, especially bigger stones, and stones with brighter colours. Compared to blue sapphire though, parti sapphire is exceptionally good value.

Bespoke-parti-sapphire-engagement-rings-Sydney-jeweller-Lizunova-Fine-Jewels-Chifley-Square

This remarkable 5.5ct cushion cut parti sapphire displays shades of green, teal and blue. Parti sapphires of this size and colour are very rare. Image: Lizunova Fine Jewels

Sources of parti sapphire

While sapphires are most commonly sourced from Africa (Tanzania, Nigeria, Madagascar, Kenya, Malawi), Brazil, Myanmar (Burma), Pakistan (Kashmir), Sri Lanka, Thailand and United States (Montana), many of the unique parti and green sapphires hail from Australia (Queensland and New South Wales).

Sapphires were widely mined in Australia in the 1970s. Today, Australian sapphire mining is much smaller in scale, and is most commonly individual miners working on their claim. The cost and complications of sapphire mining have ensured good quality Australian sapphires are much more scarce.

Parti-sapphire-Lizunova-Fine-Jewels-Sydney-jeweller-Chifley-Square

This oval cut Australian parti sapphire displays the classic yellow and blue colours, mixing into green tones at certain angles. Image: Lizunova Fine Jewels

Treatments

Heating sapphires 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 sapphire and is a lasting treatment that does not wear off with time.

Synthetics

Parti sapphire is the only stone that can’t be synthesised in a lab, due to the patchy colour pattern.

 

SAPPHIRE SPECIFICATIONS

Hardness: 9 Mohs

Specific Gravity: 3.95-4.03 (sapphire)

Refractive Index: 1.760-1.774

Crystal Form: Trigonal. Sapphire 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

 

Image: Lizunova Fine Jewels

Sources: The Jeweller’s Directory of Gemstones,Judith Crowe ; OAGems.com

 

Parti sapphire | Parti sapphire engagement rings 

 


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Ring sizes

We use Australian ring size measurements, which are in an alphabetical range from A-Z.

As your fingers contract and expand due to the temperature, humidity, exercise, etc, your ring will fit on your finger tighter or looser. Your ring should fit comfortably and you need to find a balance between too big and too small. It is recommended that you should have to push your ring on tightly over your knuckle and it should spin slightly around the base of your finger. There should be some resistance when the ring is taken off – this will help to keep the ring on when your fingers are cold or wet. The correct size is the one that you feel the most confident and comfortable with.

We suggest that you size the finger you intend to wear your ring on at room temperature – this should provide you with a size that should be close to perfect most of the time.

Top-heavy rings can tend to spin on your finger, as the base of your finger is usually thinner than your knuckle. We suggest when sizing your finger for a top-heavy ring, that you err on the tighter side, rather than a loose fit. This will mean that the ring will stay on the top of your finger and it will ultimately be more comfortable to wear.

If you’re choosing a wide ring, you will tend to go up a size. There is more surface area on a wider ring and therefore more metal to grip to your finger.

If you are interested in a ring that is 5mm or wider, we suggest going up a size (one size larger than the sizing gauge). We suggest going up another size if the ring you are interested in is 9mm or larger (two sizes larger than the sizing gauge).

If you are buying a ring as a gift for someone, we recommend that you measure the inside diameter of a ring the person you’re buying the gift for, regularly wears on the finger your gift will be worn on.

Measuring your finger

If you do not know your ring size you can use this guide to obtain an approximate measurement.

Before measuring the finger on which the ring you’re purchasing will be worn, please ensure the following:

The number that lines up with edges of the opening is the ‘interior circumference’. Please note this number and then refer to our Ring Size Chart to choose the correct ring size.

Download Ring Size Guide PDF

If you do not know your ring size you can use this guide to obtain an approximate measurement.

If you have a ring that is worn on the finger you need sizing, print out the ring size guide (take care to print it at 100%), and place the existing ring over the circles. Measure the inside of the ring against the outside of the circle. If you can hardly see the black line which goes around each circle, you have chosen the right size. Compare the ring to the adjacent circles to check that you definitely have the right size.

You can then double check this measurement by measuring the inside diameter of the ring, and matching that against the ring diameter measurements shown.

Alternatively, if you don’t have a ring available, you can measure the finger itself to obtain an approximate ring size. You can do so by wrapping a piece of string or thin strip of paper around the finger on which you wish to wear the ring, marking it with a pen where it overlaps. Measure the piece of string with a ruler to obtain the circumference of the finger, and compare that to the European Size measurement shown on the chart. We would recommend that in order to obtain the most accurate measurement when taking your ring size in this way, you do so at the end of the day when the finger is at its largest, and not when your hands are unusually cold as this would lead to a smaller ring size.

If you require any further assistance in obtaining your ring size, please  contact us and we will be happy to help.