Laboratory grown diamonds
HPHT & CVD
The image provided by GIA contains three diamonds in rough form. Each diamond was grown by a different process. The top two diamonds from left to right are one CVD grown diamond and one Natural diamond. The lower diamond was grown using HPHT. Each one of these diamonds has their own shape, growth structure, and number of facets.
Lab Grown Diamond Prices
Lab Grown vs Natural
The chart shows the price comparison between us and other retailers. It also shows the price difference between Lab Grown Diamonds versus Mined Diamonds. Simply put, we are more affordable and would challenge any retailer to beat our prices.
HIGH PRESSURE, HIGH TEMPERATURE
HPHT Lab Grown Diamond Process
The High Pressure, High Temperature synthesis imitates natural diamond growth by simulating the same pressure and temperature required for them to grow deep in the earth.
The chart is a Diamond (carbon) Stabiltiy Chart showing the required pressure and temperature HPHT, CVD, and Natural Diamond need to form in. You can see that the HPHT process contains a slightly greater pressure and temperature than that of the Natural Diamond growth process.
Take note that CVD is located in the Graphite region for growth. We will discuss that in CVD.
Growing with High Pressure, High Temperature
HPHT Growth pods
These pods are aligned in warehouses and factories. Each one produces a Lab-Grown Diamond using the High Pressure, High Temperature method. They are grown in days or weeks. It depends on how large you want the diamond to grow.
The Anvils
Steel anvils in the Pod create an intense pressure. This simulates pressure between 5 & 6 GPa (equivalent to 150-190km down into the earth.) This can also be comparable to 80 elephants standing on your big toe.
The Cell
The cell contains a diamond seed crystal for the newly formed diamond to bond to. The heating element creates a temperature of 1300-1600°C. The carbon source (graphite or diamond powder) travels to the seed crystal by way of temperature gradient and a metal flux/ catalyst.
Growth Pattern
Structure
Here is a comparison of growth structures between a Natural Diamond and HPHT Lab Grown Diamond. If you were to laser cut (saw) each diamond where the dotted lines are, you would see different growth zoning layers.
The Natural Diamond (first column) is essentially a cubic layer of expansion from one singular point. Similar to the rings of a tree, but in a cubical aspect. It lends itself to an Octahedron shape. There are eight total sides. Imagine two four sided pyramids attached at their bases. If you cut it in half, you would see the squared layers.
The HPHT Lab Grown Diamond contains fourteen sides. It is a squatty faceted cube known as a Cuboctahedron. Growth begins at the seed crystal (seen above) and expands out, and upwards into sections. Slicing it in half will show you the four main quadrants and the surrounding sections.
Therefore, a large distinguishing characteristic between a Natural Diamond and this HPHT Diamond are their growth structures.
The image to the left shows HPHT Lab Grown Diamond in its rough form. From here, the lab grown diamond is manufactured (cut) further into a popular shape the allows for maximum light return.
Chemical Vapor Deposition
CVD Lab Grown Diamond Process
The CVD Lab Grown Diamond method involves diamond growth in temperatures of 700–1300°C, but pressures of less than 1 GPa within a vacuum chamber. This is in the Graphite region, where carbon cannot crystalize into Diamond. Instead of using pressure, CVD involves a vaccuum; the opposite. A plasma energy source breaks apart gas molecules; releasing carbon atoms. These carbon atoms migrate downward toward the substrate; where they bond and become diamond. CVD Lab Grown Diamond crystals are cubic in shape because they are grown on (100) orientation diamond substrate. The finished CVD diamond tablets are referred to as “As-Grown”.
The Reactor
This is a chamber CVD Lab Grown Diamonds form in. You can literally set it on a countertop. However, large control systems like the one behind it work in conjunction with the reactor. The energy source and diamond substrate can be seen up-close when viewed through the window.
The Chamber
Growth happens when a heated mixture of methane and hydrogen gases are broken down into carbon atoms by microwave plasma within the vaccuum chamber. The carbon atoms replace the hydrogen atoms on the surface of the diamond seed plates, growing diamond upward.
Growth Layer
Viewing the CVD Lab Grown Diamond slice, you can see the yellow section. This is the diamond seed crystal used. The upper colorless portion is the new CVD Lab Grown Diamond portion. The darker polycrystalline diamond grows off the seed cystal. It is removed by laser. The result of a finished CVD Lab Grown Diamond can be seen above.
Growth Pattern
Structure
A CVD Lab Grown Diamond contains numerous, tight-knit, microscopic flat vertical layers. This unique upward growth striae is characteristic of Chemical Vapor Depostion. Close identification using gemological instruments can locate these growth striations. Remember, a Natural Diamond grows in cubic layers. These striations are also a great way to tell them apart from HPHT Lab Grown Diamonds.
CVD Color Treatment
Using HPHT
Over half the CVD Diamonds grown are comprised of a light brown color. The High Pressure, High Temperature process is also used to remove the brown color in a CVD grown diamond. This is a permanent process. The diamond remains colorless.
In the end, whether you choose a CVD Lab Grown Diamond, HPHT Lab Grown Diamond, or a Natural Diamond, there are a few things they all have in common. All three of them are a Diamond. They all lend themselves to beauty, and are all given with love. However, a Natural Diamond's rarity will always be inescapable.
