Synthetic rubies and sapphires are created through a process known as the Verneuil method or flame fusion method. The process involves melting aluminum oxide (Al2O3), which is the chemical composition of both rubies and sapphires, and then allowing it to crystallize as it cools. Here's an overview of how synthetic rubies and sapphires are made:
Melting the raw materials: High-purity aluminum oxide powder, along with small amounts of coloring agents (e.g., chromium for rubies, titanium and iron for blue sapphires), is placed in a crucible and heated to very high temperatures, around 2000-2050°C (3632-3722°F), in a furnace.
Crystal growth: As the powder melts, a seed crystal (a small natural or synthetic ruby/sapphire) is lowered into the melt. The molten material rises up around the seed crystal, and as the crucible is slowly withdrawn from the furnace, it cools down, causing the alumina to crystallize and grow onto the seed.
Cooling and shaping: The crucible is continually withdrawn, and the crystal grows in the shape of a cylindrical boule. The cooling process is carefully controlled to ensure the growth of a single, large crystal without impurities.
Cutting and polishing: Once the boule has been grown to the desired size, it is cut into smaller pieces, which are then shaped and polished to create synthetic rubies and sapphires suitable for use in jewelry.
As for synthesizing diamonds using a microwave oven, it's important to clarify that the process you are referring to is not the same as the household microwave ovens used for cooking. While it is possible to create synthetic diamonds in a laboratory setting using a microwave plasma chemical vapor deposition (MPCVD) method, it is a highly specialized and complex process carried out under controlled conditions in professional laboratories.
The MPCVD process involves using a microwave reactor to create a plasma from a mixture of gases, such as hydrogen and methane. The carbon atoms in the methane separate, and the carbon atoms get deposited onto a substrate (usually a diamond seed) in a diamond lattice structure as the plasma cools. Over time, layer by layer, a synthetic diamond crystal is grown.
It's essential to note that this diamond synthesis process is sophisticated, expensive, and requires expert knowledge and equipment. It is not something that can be achieved using a standard household microwave oven. Moreover, the diamonds created through this process are primarily used for industrial purposes (e.g., cutting tools, abrasives, electronics) rather than for jewelry, as the process tends to produce small and often yellowish diamonds that are not of gem quality. High-quality gem-grade diamonds are still predominantly sourced from natural deposits.