Memorial diamonds — also called cremation diamonds, hair diamonds, or biography stones — are genuine diamonds grown from the carbon in a person's or pet's hair. The process uses the same fundamental physics that forms diamonds deep within the Earth, replicated in a laboratory over approximately 50 days.

The result is a stone that is physically, chemically, and optically identical to a mined diamond. It is not a simulant (not cubic zirconia, not moissanite, not glass). It is carbon, in a cubic crystal structure, with the same hardness, brilliance, and properties as any diamond pulled from the ground.

Here is exactly how it works.

The Science: Why Hair Contains a Diamond

Hair is approximately 45–51% carbon by mass. That carbon is locked into the protein keratin — the same fibrous protein that forms nails, wool, feathers, and hooves. Keratin is remarkably carbon-dense, which is why hair is an ideal source material for diamond creation.

Diamonds are entirely carbon. Not a compound, not an alloy — pure elemental carbon (symbol C, atomic number 6), arranged in a specific tetrahedral crystal lattice called a cubic structure. Every carbon atom bonds to four others in this lattice, which is what gives diamonds their extraordinary hardness (10 on the Mohs scale — the hardest natural substance).

When carbon from hair is purified and placed under the right conditions — extreme heat and pressure — it crystallises into exactly that structure. The atoms bond, the crystal grows, and a diamond forms. The fact that the carbon came from hair rather than a geological deposit doesn't change the crystal it produces. Chemistry is chemistry.

Key fact: A memorial diamond is not a copy of a diamond, a simulant, or a diamond-like material. It is a diamond. The same carbon atoms, the same cubic crystal structure, the same properties. It will scratch glass, pass a thermal conductivity test, and refract light identically to any other diamond.

The 5-Step Process

At Silmaril, we follow a five-stage process from the moment we receive your hair sample to the moment your finished jewellery is returned to you.

1

Hair sample submission

We post a secure collection kit to your New Zealand address. The kit contains a sample bag, instructions, and a return envelope. You collect the hair — approximately 10g for human hair, or approximately 20g for pet fur (animal fur has lower carbon density than human hair) — seal it in the provided bag, and return it to us by post. Unused hair is returned to you with the finished diamond.

2

Life-ID assignment

On arrival at our Auckland facility, your sample is logged and assigned a unique biological Life-ID. This identifier is physically attached to your sample and tracked through every subsequent stage of production. Each stage is photographed, creating a visual chain of custody. Milestone photos are available to you on request. From this point, your loved one's material is never combined with anyone else's — One Guest, One Chamber, always.

3

Carbon extraction and purification

The hair is subjected to a controlled chemical process that isolates the carbon from the keratin, removing all other elements — hydrogen, nitrogen, sulphur, oxygen — that make up the hair's amino acid chains. The resulting carbon is then purified to 99.99% purity. This high-purity carbon is the raw material that will become your diamond. Any impurities at this stage would compromise crystal quality, so purification is critical.

4

HPHT crystal growth (~50 days)

The purified carbon is loaded into a dedicated HPHT (High Pressure High Temperature) growth chamber alongside a small diamond seed crystal and a catalyst. The chamber is sealed and brought to conditions exceeding 1,300°C and 5 GPa (approximately 50,000 times atmospheric pressure) — replicating the conditions in the Earth's mantle, 150–200 km below the surface, where natural diamonds form.

Under these conditions, the carbon dissolves into the catalyst and precipitates onto the seed crystal, atom by atom, in the cubic crystal structure of diamond. The growth process takes approximately 50 days. At the end, a rough diamond crystal — your diamond — is removed from the chamber.

5

Cutting, setting, and delivery

The rough diamond is cut by a gemologist into the chosen facet pattern, polished to finished gem quality, and set into your chosen jewellery design — either The Guardian (18K white gold, dangling horseshoe pendant) or The Warmth (18K yellow gold, integrated horseshoe pendant). The finished piece is inspected, packaged, and returned to you by insured courier to any New Zealand address. GIA or IGI certification can be arranged on request.

What Quality Can You Expect?

Silmaril's HPHT diamonds consistently achieve VS to VVS clarity (Very Slight to Very Very Slight inclusions) and D to H colour (colourless to near-colourless). These are industry-standard grades used for all diamonds — mined and lab-grown alike.

To put those grades in context:

Every Silmaril diamond is a 0.57ct stone. If you would like GIA or IGI gemological certification, contact us at [email protected] for current certification pricing.

HPHT vs CVD — What's the Difference?

There are two main methods for creating lab-grown diamonds: HPHT and CVD (Chemical Vapour Deposition). Memorial diamond studios — including Silmaril — use HPHT, for a specific reason.

CVD grows diamonds from a carbon-rich gas in a low-pressure chamber. The process can produce very large diamonds efficiently, but it requires the carbon to be in gaseous form. Carbon from hair cannot be converted to CVD-compatible gas without losing the provenance of the material.

HPHT, by contrast, works with solid carbon. The purified carbon from hair is placed directly into the growth chamber, meaning the diamond that grows is genuinely made from your loved one's material. This traceability is why HPHT is the standard for memorial diamonds across the industry.

Summary: HPHT is the only method that allows carbon from hair to be directly grown into a diamond without converting it to a different form. It is the appropriate technology for memorial diamond creation — not a compromise.

Why Not Ashes?

Cremation ashes are often misunderstood as a viable source of carbon for diamond creation. In reality, the cremation process changes the chemistry of the remains significantly.

When a body is cremated at 760–1150°C, most organic carbon is burned off. What remains is predominantly calcium phosphate (from bone), along with metal oxides, silica, and other mineral compounds. The carbon content is minimal and the impurity levels are high — both incompatible with the HPHT process, which requires 99.99% pure carbon.

Hair, by contrast, is rich in keratin and retains its carbon through normal collection. A 10g hair sample yields sufficient pure carbon to grow a 0.57ct diamond. Ashes cannot replicate this.

Silmaril works exclusively with hair. If you are in a situation where only ashes are available, we explain the options on our ashes-to-diamond page.

Is the Diamond Traceable to My Loved One?

This is the most important question most people ask, and the answer is yes — through three layers of assurance:

  1. One Guest, One Chamber protocol: Your hair sample is placed in a dedicated HPHT chamber. No other customer's material is ever present. This is a physical operational guarantee, not just a policy.
  2. Life-ID tracking: Your sample receives a unique identifier on arrival that follows it through every stage — logged, labelled, and never separated from your material through purification, growth, cutting, and setting.
  3. Photographic documentation: Each production stage is photographed and tagged to your Life-ID. You can request milestone photos at any point in the process.

The combination of physical separation (dedicated chambers), documentary tracking (Life-ID), and visual evidence (photographs) provides a layered chain of custody that goes beyond what most providers offer.