CVD diamonds have been around since the 1960s, and are named after the process by which they are grown. But how do they compare to HPHT (high-pressure, high-temperature) diamonds? Here’s what you need to know about the differences between these two types of diamonds and how you can use this information to make an informed purchasing decision.
1)Origin
While both types of diamonds are created in a lab, their starting materials vary greatly. In HPHT, synthetic diamonds begin as methane gas and are superheated under extreme pressure. In CVD diamonds, natural or synthetic graphite (like pencil lead) is coated with chemicals called hydrocarbons—such as methane, acetylene, or ethylene—that will serve as carbon precursors to grow a diamond. Depending on what precursor you use, you’ll end up with a different type of diamond. For example, if your coating consists of methane and hydrogen in equal parts by volume at 1 atmosphere (1 atm), you’ll get an amorphous diamond.
2) Color
One of many ways in which CVD diamonds and HPHT diamonds differ is in their color grades. Natural mined diamonds come in a variety of different colors but are generally limited to either near-colourless or fancy colored diamonds. The specific grading systems used to describe natural color are known as the Gemological Institute of America (GIA) and the International Gemological Institute (IGI). A diamond with a GIA grade D-F will appear white under normal lighting conditions, while one graded from G-J will have more yellow or brown hues. This color grading scale is commonly used among jewelry stores and buyers, making it easy for consumers to differentiate between color quality grades on their own.
3) Shape
The process of growing diamonds through HPHT is a semi-synthetic process and results in diamonds that are often octahedral or dodecahedral. The shape of these diamonds will determine how they’re set in jewelry, but most likely, an appraiser will refer to them as OEC (octahedral) or DAE (dodecahedral). These terms just mean that they were grown at high pressure and high temperature in order to reach their final shapes. While it doesn’t necessarily affect value, it might be worth noting that CVD diamonds are often not quite as well-shaped as rhtd (room temperature high pressure) stones.
4) Transparency
Natural diamonds are transparent, offering you a glimpse into their inner beauty and quality. But that doesn’t mean all diamonds are created equal; not only does transparency differ from stone to stone, but it can also be affected by cutting and polishing. More often than not, diamond cutters will polish away any traces of internal cloudiness to give a diamond an optimal level of clarity, which means you might not be able to appreciate or see a diamond’s true color until it has been set in jewelry. This is one of many reasons it is important to buy a certificate along with your diamond—otherwise, you may end up disappointed with your purchase.
5) Cut
The cut of a diamond can either make or break its beauty. The cut is one of the 4Cs and is defined as how well a diamond’s facets align with and reflect light. There are many different types of diamond cuts that affect both appearance and price, each with its own pros and cons. One of these is HPHT vs. CVD-grown diamonds.HPHT stands for High-Pressure High Temperature, while CVD is Chemical Vapor Deposition. Both are laboratory-grown stones, but what is better? Here’s an overview of both types of cuts to help you decide which fits your needs best!
6) Hardness
One of the biggest differences between HPHT and CVD diamonds is hardness. Due to their natural formation process, HPHT diamonds have higher hardness than CVD diamonds. What does that mean for you? It means that, when shopping for a diamond, it’s important to compare only those with similar hardness levels. An extremely hard diamond could scratch something softer like an everyday wine glass or butter knife; an extremely soft diamond could be scratched by something with a harder surface like your fingernail or keys. lab created diamonds ensure your purchase will last a lifetime and beyond, look for a stone in a hard-to-soft range of 8.5 to 9 on Mohs’ scale (the typical value given is 8). This will ensure both durability and beauty!
7) Carat Weight
CVD can only be grown in small sizes, with larger stones rare and expensive. These days, it’s possible to grow a 3-carat stone via HPHT. Natural diamonds generally weigh between one-third and 2 carats per carat of rough. Therefore, a 1-carat natural diamond will typically yield 0.33 to 0.67 grams of gem-grade finished product from its original rough form. Best Lab Grown Diamond Manufacturer.
8) Cost
The quality of diamonds increases with price. For example, a 3-carat HPHT diamond that has an I-color grade will cost about $4,000 more than a 3-carat CVD diamond that also has an I-color grade. When you factor in other costs, like setting and general upkeep, you’ll see that overall HPHT and CVD cost about the same. Of course, if you’re looking for a truly larger stone—9 or 10 carats—HPHT is going to cost more than CVD diamonds.
