DIAMOND GUIDE
At SARAH & SEBASTIAN we take a pragmatic and transparent approach when it comes to engagement and wedding rings. We understand that the process can be over-romanced and under-informed, with an abundance of choice on the market and limited or misleading information.
For us the starting point is always the diamond. We have a trained team of jewellers, diamond graders and gemologists who are passionate about choosing the most beautiful, ethically sourced, GIA certified stones. We’re firm believers in quality over quantity and will never compromise on the stones we choose.
We handpick our diamonds specifically for each client’s engagement ring to ensure we have sourced the best possible stone at that time. This means no two of our rings are ever the same and we can work closely with our clients to meet their requirements and budgets.
Below you will find a guide explaining diamond properties and how these relate to each grading system. If you have any further questions outside of the stipulated information, please contact us as we have diamond graders and gemologists available to answer any question you may have.
Our white diamonds are hand selected to match our strict criteria, with each stone meeting a high quality of brilliance, clarity, cut and colour. Our white diamonds are certified by the Gemological Institute of America (GIA). GIA is the largest, most respected nonprofit source of gemological knowledge in the world. As a long-standing scientific authority, its grading reports inspire confidence wherever they appear. GIA’s commitment to protecting diamond buyers led the Institute to create the Diamond 4Cs and the International Diamond Grading System™. These methods are the universal benchmarks by which all diamonds are judged. As the birthplace of these standards, and with its ongoing investment in gemological research, GIA’s authority is unequaled.
Diamond colour is all about what you can’t see. Diamonds are valued by how closely they approach “colourlessness” – the less colour, the higher their value. (The exception to this is fancy colour diamonds, such as pinks and blues, which lie outside this colour range.)
The subtleties of colour are such that even experts cannot absolutely determine a diamond’s colour simply by visual estimation of a single stone.
GIA’s colour-grading scale for diamonds is the industry standard. The scale begins with the letter D, representing colourless, and continues with increasing presence of colour to the letter Z, or light yellow or brown.
Each letter grade has a clearly defined range of colour appearance. Diamonds are colour-graded by comparing them to stones of known colour under controlled lighting and precise viewing conditions.
SARAH & SEBASTIAN diamonds run from colourless to near-colourless (D-G), with slight hints of yellow or brown.
Inclusions in diamonds are guarantees of the natural evolution of the original diamond crystal. Because diamonds form deep within the earth, under extreme heat and pressure, they often contain unique birthmarks, either internal (inclusions) or external (blemishes).
These inclusions can be present in either the form of mineral specimens, fractures, cleavage or tension cracks. There are approximately 25 minerals which are known to be found as inclusions in diamonds; some of the most common are garnet and spinel. The other types of inclusions present will be as a result of disturbed crystal growth.
Diamond clarity refers to the absence of these inclusions and blemishes. Diamonds without these birthmarks are rare, and rarity affects a diamond’s value. Using the GIA International Diamond Grading System™, diamonds are assigned a clarity grade that ranges from flawless (FL) to diamonds with obvious inclusions (I3).
Every diamond is unique. None are absolutely perfect under 10× (loupe) magnification, though some may come close. Known as Flawless diamonds, they are exceptionally rare. SARAH & SEBASTIAN sources diamonds graded by GIA using the GIA Clarity Scale. This scale contains 11 grades, with most diamonds falling into the VS (very slightly included) or SI (slightly included) categories.
SARAH & SEBASTIAN source diamonds in the clarity range from IF – SI1 with the majority of stones in the VVS – VS range. Our in-house gemologists select stones that are eye clean, with any visible inclusions positioned in such a way that they may be concealed by a setting, are colourless, or are in an area that does impact the brilliance or overall appearance of the stone.
A carat refers to the total weight of a diamond; this translates into the diamond’s physical size. Essentially, diamond carat weight is the measurement of how much a diamond weighs. A metric “carat” is defined as 0.2 grams.
All else being equal, diamond price increases with carat weight, because larger diamonds are more rare and more desirable. But two diamonds of equal carat weight can have very different values (and prices) depending on three other factors within the 4Cs: Clarity, Color, and Cut.
It’s important to remember that a diamond’s value is determined using all of the 4Cs, not just carat weight.
For diamonds that are equal in every way, diamond value increases as weight increases. At certain weight boundaries, occasionally called “magic sizes,” the price per carat increases significantly. That’s because these boundaries or thresholds coincide with popular weights, and popularity means greater demand and therefore higher prices for these weights. This is especially true at the magic one-carat size. SARAH & SEBASTIAN is pleased to source diamonds in any carat weight above 0.5ct within our parameters of the 4c’s.
The “Cut” of a diamond is the most important factor of a diamond’s appearance. Although colour and clarity are important factors for diamond value, the allure and beauty of a particular diamond depends more on cut quality than anything else. Cut refers to the way the facets of a diamond interact with light and how bright and lively it appears, which can be noticed without any formal training. Cut relates directly to the diamond’s fire, sparkle and brilliance.
Our priority is to offer a diamond that is well proportioned, aiming to feature an ‘Excellent’ to ‘Very Good’ cut grade. When choosing a diamond, our gemmologist will also consider the ‘spread’ of the stone, ensuring the proportions are still within the SARAH & SEBASTIAN parameters while sourcing the largest ‘face up’ appearance of the stone within the client's desired carat range.
Our champagne diamonds are ethically sourced from Australia’s renowned Argyle Mine in Western Australia. We are proud to celebrate a stone that shares the same heritage as our brand, and captures the natural hues and warm tones of the Australian landscape.
Australian champagne diamonds are graded against the Argyle Colour Grading Scale, ranging from a light Beige (C1) to dark chocolate (C7) in colour. The colouring is 100% natural, providing each stone with a unique shade and increased rarity.
SARAH & SEBASTIAN source C3 - C4 champagne diamonds which have been carefully selected to complement the warm tones of yellow and rose gold, and cut specifically to maximize colour and brilliance.
