What two inventions made mass production of faceted diamonds possible?

• A. The invention of a small hand-held saw used for rough shaping.
• B. The inventions of the bruting machine and the motorized diamond saw made mass production of faceted diamonds possible.
• C. The introduction of continuous rotary motion and cast-iron polishing wheel.
• D. The use of water-based lubricants during polishing.

Answer: (B)

Mass production of faceted diamonds hinges on two key advances that dramatically speed up and standardize the early stages of diamond preparation. The first is a machine that shapes rough diamonds into a uniform girdle form, known as bruting. When two rough stones are rotated against each other in a bruting machine, they produce a precise, round outline with consistent symmetry. This replaces slow, irregular hand bruting and creates standardized preforms that faceters can work from, making large-scale production feasible.

The second is a motorized diamond saw, which allows rapid and consistent removal of material to form workable preforms. This dramatically speeds up the initial cutting stage and ensures uniform thickness and shape across many stones, laying the groundwork for efficient faceting. Together, these two inventions introduced reproducible, high-throughput workflows that underpin mass production.

Other listed ideas describe improvements that are helpful but not the defining breakthroughs for large-scale production. A small hand-held saw is too slow for high-volume work, while continuous rotary motion and cast-iron polishing wheels, or the use of water-based lubricants, don’t by themselves enable the same leap in throughput and standardization.