At SARAH & SEBASTIAN, our team of gemologists including our Creative Director Sarah Munro are passionate about diamonds. We handpick every diamond that features on one of our engagement rings and are big believers in quality over quantity when it comes to gemstones. 

Whilst the majority of natural white diamonds we source are ethically mined and GIA certified, more recently clients have been requesting lab grown or cultured diamonds as a ‘sustainable’ alternative. As we can source lab grown diamonds upon request, we wanted to share a little insight on these stones, how they compare to natural diamonds and our views.


Natural diamonds are created by the earth; true miracles of nature. A result of heat, pressure, carbon and billions of years, diamonds are formed and stored deep in the earth’s mantle. Critical amounts of temperature and pressure are needed for natural diamond formation and stability where the carbon atoms bond together under the extreme environment, creating a diamond. They are then transported to the earth’s surface during natural events, often through volcanic eruptions and remain in rock formations before they are mined.

engagement ring

Lab grown diamonds, otherwise known as cultured, man-made or synthetic diamonds, are created in a controlled laboratory environment that replicates similar conditions. With two main methods, Chemical Vapor Deposition (CVD) and High Pressure High Temperature (HPHT), unlike the billions of years it takes to create mined diamonds, these methods allow less than a month to produce lab grown diamonds.

HPHT diamond growth takes place in a small capsule capable of generating very high pressures, meant to replicate the natural conditions within the earth. Whereas CVD diamonds grow from a hydrocarbon gas mixture, subjected to moderate pressures and temperatures in a vacuum chamber. Both methods allow for crystallisation to occur over a period of several days to weeks, growing several gems at a time.

At SARAH & SEBASTIAN, we prefer CVD when choosing to work with lab-grown diamonds, as this process does not use any post treatments, unlike HPHT which uses a heat treatment to improve colour quality.

Sarah Munro


Made from a crystallised carbon structure, they have the same chemical, physical and optical properties as mined diamonds - the only difference is their origin. Distinguishing between the two requires a trained gemologist and sophisticated equipment specifically designed for identifying lab grown diamonds. To the naked eye, they are the same.

Due to their physical and optical similarities, they are graded on the same 4Cs of diamond quality (carat, cut, colour and clarity), which determine how much a diamond is worth. However, because lab diamonds are fairly new to the market, they are currently less expensive and average 30-50% less than a natural diamond.

Clarity: The quality of diamonds that relates to the visual appearance of internal characteristics of a diamond, namely mineral inclusions and blemishes; a stone’s grading will depend on how many and the position. Since a perfect stone is extremely rare, most stones will have some inclusions, but whether they are noticeable to the naked eye will determine their price point.

Cut: Perhaps the most important of the four Cs, the cut refers to the facets, symmetry, and reflective qualities of a diamond, contributing to its overall sparkle and beauty. The better a diamond has been cut, the greater the diamond’s ability to reflect and refract light. The higher the grade, the more light the stone will reflect.

Colour: Although all diamonds (mined or lab-grown) are made from a crystallised carbon structure, a stone’s makeup can differ due to trace elements other than pure carbon during the formation - which causes a slight yellow in colour. The highest quality of diamonds are colourless, whereas lower quality diamonds can often have a slight yellow tint. This is measured using the GIA colour scale, which ranges from D (colourless) to Z (light yellow). 

Carat: This refers to the unique unit of weight measurement, used exclusively to weigh gems and diamonds. Diamond price increases with carat weight, as larger diamonds are more valuable due to their rare discovery in nature, whereas lab grown diamonds can be grown for a longer period of time to reach a larger size. However, two diamonds of equally carat weight can be valued differently depending on the three other factors of the diamond.


All of our SARAH & SEBASTIAN natural white diamonds have GIA certification, where diamonds are examined by a minimum of four highly trained diamond graders and gemologists. Like natural diamonds, our lab-grown diamonds also have certification from either IGI or GCAL. These reports include a grade for each of the 4 Cs as well as verification that it was naturally mined or lab-grown.


We occasionally do blind tests in the workshop to compare natural and lab grown diamonds and most of the time, our team usually pick up extra sparkle from the natural stones. As storytellers, we’re also drawn to the wonder of how natural diamonds originate and their ancient history. Because of this, we prefer to use natural diamonds for our engagement rings and recommend lab-grown diamonds for other special pieces like anniversary gifts.

When deciding to embark on your diamond journey, it’s always best to be informed. Equipped with the right information about how diamonds are made, their appearance and price, it’s easier to find the perfect diamond for you. Whether you choose a natural or lab-grown diamond, there is no right or wrong - only what is important to you.