Orders for diamonds made from human cremains aren't the only type that Algordanza receives. "First we had the cremains of a German Shepard and now we have cremains of a cat," Martoia said.
Algordanza's prices start at $3,000 for a 0.3 carat diamond. Martoia said the average order is about 0.4 to 0.5 carat, though US customers usually request bigger, 0.8-carat diamonds.
But Algordanza can make them much larger: The company recently took a $48,000 order for 2-carat diamond. After 10 months of growth, the resulting gem actually wound up being 1.76-carats — but it's still the largest memorial diamond ever made by the company.
Some customers take the rough gem, but many opt to have their memorial diamonds cut, faceted, and polished by a jeweler in Switzerland.
When enough time has passed, technicians remove the puck of graphite and crack it open.
Source: Science Channel
Depending on how big a customer wants their diamond to be, it can take six to eight weeks in an HPHT machine to coax graphite to crystallize into a gem. "The larger the diamond, the longer it takes to grow," Martoia said.
That's like the entire mass of the International Space Station bearing down on the face of a wristwatch — then heating it up to a temperature exceeding that of lava.
That machine can heat a growth cell to nearly 2,500 degrees Fahrenheit. It also squeezes the cell under 870,000 pounds-per-square-inch of pressure.
Source: Algordanza
To emulate that environment, Algordanza inserts the cell (now packed with graphite) into a platter and slides it into a high-temperature high-pressure (HPHT) growing machine.
Natural diamonds form out of carbon that gets stuck in lava tubes about a mile deep in the Earth's crust.
The final purification step converts the carbon into slippery sheets of graphite — the same type of carbon in pencils. Graphite's microscopic flat sheets of carbon are an ideal starter material for synthesizing diamonds.
The cell also contains a tiny diamond to help the carbon crystallize into a rough shape, since carbon crystallizes best when it touches an existing diamond.
The diamond provides a "blueprint" for the carbon to work from, which means the new diamond that eventually forms will require less cutting and polishing.
To further purify the carbon to 99.9% or more, technicians pack it into a growing cell that contains iron and cobalt — additives that help remove contaminants.
When Algordanza processes ashes, Martoia says, "it's nearly impossible to separate out the boron from the carbon". This is because the two elements share similar weights and properties.
"The diamonds can range from clear to very deep blue," Martoia said. "The more boron, the deeper the blue."
She added that it's impossible to predict the exact color a memorial diamond will take on.
"But an interesting thing to note is that our technicians are seeing a correlation in people who have had chemotherapy. Their diamonds tend to come out much lighter," Martoia said. This may be because chemotherapy leaches away the body's boron and other important micronutrients.
Boron is the impurity that colors the rare blue diamonds found in nature — and is why many "memorial diamonds" come out blue, too.
Source: Gemological Institute of America
The other 1% contains impurities like boron — an element and micro-nutrient that helps humans (and other animals) grow bone, heal wounds, and regulate the immune system.
Once there's enough carbon, the element is extracted and purified of contaminants like salts. "We use an acidic chemical to get rid of impurities," Martoia said.
When the company receives ashes from a customer, a technician puts a sample into a special oven to see if there's enough carbon to grow a diamond. If there's not enough, the amount of carbon in a lock of hair can make up the difference.
Martoia said Algordanza requires a minimum of one pound of cremains. "That's kind of the magic number, where our engineers can guarantee there will be enough carbon to make a memorial diamond," she said.
Making a diamond from a dead person begins with cremation. The process typically leaves behind about 5 to 10 pounds of ashes, much of which is carbon.
Styles of cremation differ from culture to culture. Some use hotter temperatures for longer, which allows more carbon to escape into the air as carbon dioxide (which may mean more ashes are needed to form a diamond).
Source: Algordanza