- LAB GROWN DIAMONDS
CVD Diamonds
CVD diamonds are identical to natural diamonds but made in the lab by Chemical Vapour Deposition. Learn how CVD diamonds are made, if and how they different to other lab and natural diamonds, and if a CVD diamond is right for you.
BOOK TO VIEW LAB DIAMONDS - What is a CVD diamond?CVD stands for Chemical Vapour Deposition, and is the commonly used name for diamonds grown in a laboratory via a process of chemical vapour deposition. This differs from another process commonly-used to create lab grown diamonds, HPHT (High Pressure High Temperature).CVD diamonds are human-made diamonds, but are identical to natural diamonds and are 100% authentic diamonds. In fact, it is impossible to tell a CVD diamond apart from a natural diamond without specialist equipment. Learn more about lab diamonds vs natural diamonds.Lab diamonds are becoming an increasingly popular choice amongst engagement ring and jewellery buyers - and along with HPHT, CVD is one of the most commonly used production methods. Some of the benefits of CVD diamond jewellery include more ethical origins, sustainability and cheaper prices – although you should be aware that CVD diamonds are typically lower quality than HPHT diamonds. As CVD diamonds increase in popularity, Kodko’s gemmologists boast specialist expertise in the field of sourcing and selecting beautiful CVD diamonds for the best value for money.
- Properties of a CVD diamondCVD diamonds have the exact same properties as natural diamonds, possessing the same internal structure, chemical makeup and physical, lustrous beauty. Just like natural diamonds, CVD diamond properties include great durability, reaching 10 of the Mohs scale of hardness, and intense brilliance and sparkle.While it is not possible to tell a lab-created CVD diamond from a natural diamond of the same quality, you should be aware that CVD diamonds often have less desirable traits, like brown tints and internal graining. This means they often require post-growth treatment. You will find HPHT lab-created diamonds are typically higher quality than CVD diamonds.
Just like natural diamonds, CVD diamonds are graded for cut, colour, clarity and carat weight. Whilst CVD are human-engineered, they are subject to the same flaws as natural diamonds, and can pick up colour tints and internal flaws while they grow. It is incredibly rare to find totally flawless CVD diamonds - some will be heavily included and poorly coloured, while others will be totally colourless, with only minuscule imperfections; just like natural diamonds. Look between SI1 and VS1 clarity grades, and D to F colour grades, for a diamond that appears top quality and provides value for money.
The reality is, even top gemmologists cannot tell a CVD diamond apart from a natural diamond. This is because CVD diamonds are diamonds, with the exact same chemical, physical and optical properties, and even the same flaws. When you buy a CVD diamond, its origin will be noted on the GIA or IGI certification. Other than this, you’d need specialist laboratory equipment to tell the diamond was human-made.
Chemical Vapour Deposition (CVD) diamond making process
1. A thin diamond seed is selected and placed in a sealed chamber
2. The chamber is heated to around 800°C and flooded with carbon rich gas
3. The gas ionises, breaking down into pure carbon
4. The pure carbon molecules attach to the original diamond seed
5. This process continues until a fully formed diamond is created
CVD diamond creation requires a highly-specialised, scientific process that has been perfected over many decades, to produce jewellery-quality diamonds in an efficient and relatively speedy way. Chemical vapour deposition is a scientific process used to create a number of solid materials, often for use in the semiconductor industry - that has been adapted to create diamonds in two to four weeks.
A thin slice of diamond, around 300 microns thick and 10x10mm, known as a ‘diamond seed’, is selected and thoroughly cleaned. The diamond seed must be clean, as any trace elements or imperfections will be crystallised during CVD diamond growth, creating inclusions and blemishes. This diamond slice is typically taken from a high quality diamond created by HPHT.
The diamond seed is placed into a sealed chamber which is heated to around 800°C. The chamber is flooded with carbon rich gas. The chamber must be completely sealed, to avoid any other gases from entering and disrupting the diamond’s growth.
The carbon rich gas ionises under the intense heat, meaning its molecular bonds break down and settle on the existing diamond seed. The pure carbon molecules bond to the diamond seed, building and building as more gas ionises and bonds to the existing diamond. This crystallisation continues until a fully formed, rough diamond is produced, and the process is ended.
CVD diamonds are grown very quickly, which can cause less beautiful traits, like graining, spotty inclusions and brown tints. These can be removed or improved with a post-growth HPHT treatment. This improves the overall look of the diamond, but may causes milkiness. Therefore, its best to find a CVD diamond that hasn't undergone post-growth treatment! This will be mentioned on the diamond's certificate.
Following creation, a CVD diamond continues to have a similar journey to a natural diamond - it will be professionally cut to the required shape, and meticulously polished to produce optimal sparkle and brilliance. Then, the diamond will be graded and certified by independent laboratories like GIA and IGI, before entering the jewellery market to be traded by diamond dealers. Jewellers like Kodko will scour the market to find the best CVD diamonds to show their clients, taking into account the diamond’s official certification, beauty and price.
- How fast do CVD diamonds grow?The speed of a CVD diamond’s growth depends on the end-goal size of the stone and the efficiency of the technologies used. Top CVD diamond producers can create 1ct diamonds in less than a month, and slightly smaller diamonds in as little as two weeks. Fancy colour diamonds, like yellow CVD diamonds, can take between 5 and 10 days, because the nitrogen added to create the yellow colour speeds up the crystallisation process.
CVD vs HPHT diamonds
An HPHT diamond is created using a process called High Pressure High Temperature, whereas a CVD diamond is created by using Chemical Vapour Deposition.
Instead of using gas, the HPHT process involves mimicking the natural diamond-making process where high levels of pressure and temperature within the earth create diamonds over millions of years. Similar to CVD diamonds, HPHT diamonds only take a few weeks to form, though this method does require higher levels of energy. Experts find that HPHT diamonds are typically created to a better quality than CVD diamonds and less frequently require post-growth treatment.
The main difference between rough CVD and HPHT diamonds is their formation. CVD diamonds grow into a cubic shape, whereas HPHT diamonds grow into a cuboctahedron. Only a carefully trained expert would be able to tell the difference, though.
You’ll also find that some labs start off with the less energy-intensive CVD process, before finishing off the diamonds with HPHT. This is because HPHT can help provide impressive clarity and colour, however, both CVD and HPHT diamonds are chemically, physically and optically identical to natural diamonds.
How do you identify a CVD diamond?
It is not possible to identify a CVD diamond apart from a natural diamond without specialist laboratory equipment and gemmological knowledge, because they are identical. Just like natural diamonds, CVD diamonds can be found in a range of qualities and grades - but compare two with the same grades and you wont see a difference. This is great news for CVD diamond buyers, who might otherwise worry that a CVD diamond could appear fake or different from a natural diamond.
Technically, when you look at a CVD diamond under magnification, you may be able to tell the diamond has different strain patterns to natural diamonds. It would require specialist gemmological knowledge to know what to look for, and even top gemmologists could struggle to see the difference.
Equipment can be used by diamond laboratories to tell if a diamond is CVD created, to look for minute trace elements like silicone, which could be picked up during creation. The knowledge and equipment needed is highly specialised, and you’d be required to submit your diamond to a laboratory like GIA.
When you buy a CVD diamond, make sure it is certified GIA or IGI. The accompanying certificate will outline whether the diamonds are natural or lab created via CVD or HPHT - and crucially, whether the diamond has required a post-growth treatment to get it looking up to scratch. Diamonds with post-growth treatments are best avoided.
CVD grading and certification
Just like mined diamonds, CVD diamonds are graded for their cut, colour, clarity, carat weight, and other details like their fluorescence, polish and symmetry. There are a number of grading labs across the world that certify lab diamonds, but the most renowned and trusted are GIA and IGI.
Both GIA and IGI assess CVD diamonds for their characteristics, to give an accurate reading of their quality, which then guides the pricing of the stone. GIA and IGI laser imprint a unique code on the girdle of the stone, only viewable under magnification, which corresponds to the paper (or digital) certificate, where you’ll find all the details of the stone, including the grades, carat weight and measurements. The certificate will also confirm if the diamond was created by CVD, HPHT, or if it is a natural diamond.
At Kodko, we always advise you only buy lab diamonds certified by GIA and IGI. Every diamond we stock has been vetted and selected by our gemmologists for both value for money and beautiful aesthetics - and we only source GIA certified diamonds and IGI certified diamonds.
- How much do CVD lab diamonds cost?The price of a CVD diamond can be significantly less than a natural diamond. This is because CVD diamonds are created in a laboratory through an efficient process that typically takes less than one month. In comparison, natural diamonds take billions of years to form, and mining companies must invest a great deal of time and money to acquire land, excavate the land and build mines, and employ a large workforce. CVD diamonds require investment in specialist (expensive) equipment and a highly skilled workforce, yet the process is efficient and overall more cost effective than mining.
CVD diamond price vs natural diamond
Both CVD and HPHT lab diamonds are usually between 50% to 80% cheaper than natural diamonds. They are, however, still high-value items, and are a precious, valuable commodity that cost thousands of pounds. A lot of work and professional expertise goes into creating, cutting, polishing and grading a CVD diamond.
The future value of lab diamonds is not certain as they are relatively new to the market, and it is unclear whether they will retain value. Experts predict that lab diamonds will never be cheap, and will always be a significant investment as the HPHT and CVD processes require investment in high-level technology, expertise and time. Some even suggest the cost of lab diamonds could increase in the future as demand rises.
Compare lab diamond vs natural diamonds prices.
- Is a CVD diamond right for me?
Actually, our advise is to choose a lab-created HPHT diamond over a CVD diamond; they are more consistently of a top quality and don't feature the signature milkiness of a post-growth treated CVD diamond.
The choice between natural vs lab diamonds is a more personal decision. To put the debate in plain terms, you’re choosing between a less expensive, more ethical and ecologically sustainable option (the CVD or HPHT diamond) versus a wonder of nature created over billions of years (the natural diamond).
Each of our consultants are trained and deeply knowledgeable about both lab grown and natural diamonds. To help you reach your decision, we can show you a range of the best lab vs natural diamonds for your preferences and budget. Get in touch to speak to our experts.
