Diamond Industry

Components for Synthetic Diamond Manufacture

Wonderstone Ltd a subsidiary of Assore Ltd. has been mining a uniquely pure Pyrophyllite deposit, found in South Africa, since 1937. Wonderstone’s unique high density pyrophyllite has been used in the synthetic diamond industry for more than 60 years. we are also happy to report that, given our current rate of mining and market demand, and based on the in-situ resource, Wonderstone still has a remaining life of mine in excess of 100 years.

Wonderstone as a company does not manufacture or sell synthetic diamonds (lab grown diamonds), we do however manufacture various components made from our unique high density Pyrophyllite. These components are mostly used as capsules / envelopes and gaskets in High Pressure High Temperature (HPHT) diamond synthesis processes. We have the capability produce these components ether through powder pressing our pyrophyllite or by directly machining from our natural pyrophyllite stone. The choice between powder pressed or natural pyrophyllite components would depend on the specifics of the application, as each form offers slightly different benefits with both offering an optimal balance between flow (gasket formation) and pressure transfer.

The mineral Pyrophyllite has played an integral role in the process of manufacturing synthetic diamonds ever since their discovery in 1954. Wonderstone has been the product of choice, because of its properties of thermal and electrical insulation and high compressive strength, while showing excellent gasket forming and pressure transfer properties even under extreme operating conditions
(>1,400 ºC, > 80 kbar).

Wonderstone is easily machined with standard machine tools and has the appropriate frictional and extrusion characteristics to form a gasket either between the die cavity and the two ramming punches in a belt die set or between the anvils in multi-anvil systems such as cubic presses.  Wonderstone Ltd. has worked hard to accommodate the special needs of its clients through its ability to machine special shapes and designs to the tight tolerances (± 50 micron) and specifications. Products produced for High Pressure High Temperature (HPHT) Processes include all standard products and various technical components used in either Belt Press (bushes, cones gaskets and wings) or Cubic press technologies (cubes, rings, sleeves and buttons).

The components can be manufactured / machined from natural stone or reconstituted (powder pressed) using Wonderstone powders in various particle size distributions.  Powders can also be spray dried and / or calcined and utilized in applications in the Belt presses.

Wonderstone Ltd. is proud to announce the development of newly formulated reconstituted components for Synthetic Diamond (lab grown diamond) manufacture. We offer variations on our powder pressed materials in which we are capable of producing components suitable for use in both Cubic Press and Belt Press technologies. 

We have performed in depth studies through various Universities and authorities outlining the properties of our reconstituted Wonderstone material.  Our studies have demonstrated a high Weibull modulus, this is indicative of reliability and consistency of the physical properties between batches of manufactured components. This means that for reconstituted cubes, when used in diamond capsules, they will yield at the same stress. This happens at the early stages of capsule deformation and are the beginning of the gasket formation stages, thus encouraging the formation of similar-reproducible gaskets.

Some major benefits of Wonderstone as gasket material are as follows:

* Natural Wonderstone Density ~2.75 g/cm³
* Reconstituted Wonderstone Density ~2.63 g/cm³
* Offers consistency required for cubic gasket components
* Very good thermal and electrical insulation
* Excellent pressure transfer capabilities
* Solid gasket seal and elasticity when pressure is released.

These components are exported to synthetic diamond, polycrystalline diamond (PCD) and cubic boron nitride (CBN) manufacturers in the UK, USA and Far East and utilised within South Africa.