The short answer to this question is yes, but don't denude the nut butter shelf at your local market just yet. In order to make peanut butter into diamonds, conditions of intense pressure and very high temperatures are needed, and most people cannot access these conditions. Using sophisticated scientific equipment, however, it is possible for peanut butter to be made into diamonds; the same principle can be used to turn a wide variety of things into diamonds, in fact, as diamonds are simply a form of carbon.

Natural diamonds are created through a process which takes millions of years. Conditions for diamond creation are found deep inside the Earth's crust, where temperatures are very high and pressure can get quite intense. Over millennia, carbon is compressed into the form of a diamond. Materials at meteor impact sites can also be made into diamonds, as a result of sudden high heat and pressure, although the resulting diamonds are typically very small.

When diamonds are made from peanut butter (and other substances), the substance is subjected to very high pressure while being heated. One way to create the necessary pressure involves squeezing a sample of peanut butter between two other diamonds; since diamond is the hardest substance on Earth, this technique can yield incredibly high pressure measurements. When the material is also heated to around 2,000 degrees Fahrenheit (1093 degrees Celsius), it can turn into a diamond.

The resulting diamond, however, is not much to look at. Most peanut butter diamonds are quite small, around the size of a fennel seed, and they are also discolored, due to impurities in the peanut butter. These discolorations are rarely strong enough to classify the diamond as a fancy diamond; instead, it just looks muddy. When peanut butter is made into diamonds, the goal is usually novelty, rather than a gemstone which could be sold on the open market.

Synthetic diamonds can be made from a wide variety of materials, and many other materials are more for the purpose of being made into diamonds than peanut butter. In fact, synthetic gems have reached a point of such high quality that it can be difficult to tell that they are “fakes,” as they are chemically identical to the real things. Most fancy diamonds on the market, for example, are synthetic, or they are made from natural diamonds which have been irradiated to produce the desired color.

The process which is used when peanut butter is made into diamonds can also be utilized for ashes. Several companies around the world will make memorial gems from the ashes of loved ones and pets. If you are particularly attached to a jar of peanut butter, you could probably make the necessary arrangements for a gem-quality peanut butter diamond, but be prepared to pay a hefty price; even the smallest of such gems is typically around $2,700 US Dollars (USD), and prices can reach $25,000 USD.