Diamantine is the hardest polishing paste available. It is also generally used for the finest polishing. On steel parts these are called “black polish”. Diamantine is made from diamond powder.

In the history of watchmaking, diamantine has often been used for the finest polishing. At a time when cases were not as water-resistant as they are today, it was important to polish steel parts very finely, as this surface finish reduces the risk of oxidation.

In watchmaking, diamantine is mainly used for aesthetic polishing of metals such as steel, brass, german silver and sometimes gold. For the more technical polishing required on pivots, for example, the cold-work technique is used instead, without diamantine, using a burnisher as a tool.

Avantages: It is the hardest of the polishing pastes that gives the best results.

Disadvantages: Diamantine is relatively expensive.