From Rough to Radiant: The 2026 Complete Guide to How a Diamond Is Cut and Polished

Two diamonds can share the same grade — D color, one carat — and still sparkle in visibly different ways. The reason isn't the rough crystal that formed deep within the earth. It's the human craft of cutting and polishing. A stone that nature took billions of years to create only becomes the brilliant gem we recognize after passing through the hands of a master cutter. Here is the 2026 guide to the five stages that bring a diamond's light to life.

A Diamond's Brilliance Is Decided in the Cutting Room

Of the 4Cs — carat, color, clarity and cut — cut is the only one created directly by human hands. Nature sets a stone's transparency and color, but how it captures, bends and returns light depends entirely on the cutter's design and skill. And because diamond is the hardest substance on earth, only a diamond can shape another diamond. That single fact makes polishing extraordinarily demanding, requiring the focus and judgment of a highly experienced artisan.

From Rough to Gem: The Five Stages of Diamond Polishing

1. Planning & Marking

Everything begins with deciding how best to use the rough. Using microscopes and 3D scanners, the cutter reads the shape, inclusions and crystal direction of the stone, then calculates which shape and size will yield the most valuable gem. Balancing yield (the percentage of weight retained) against beauty, this is the most intellectual stage — and a single decision can dramatically change the final brilliance and value.

2. Cleaving & Sawing

Once the plan is set, the rough is divided. Cleaving splits the crystal along its natural grain, while sawing uses lasers or ultra-thin blades to cut it. Sections containing impurities or flaws are removed here, shaping the clean foundation of the future gem. A momentary error can waste the rough entirely, making this a tense and exacting step.

3. Bruting

Next, two diamonds are spun against each other to grind the basic rounded outline. The perfect circle of a round brilliant cut is born at this stage — literally diamond shaping diamond, a process unique to this gem.

4. Polishing & Faceting

Now the facets that create the sparkle are ground and polished one by one. The stone is held against a spinning wheel called a scaife, dusted with diamond powder, while angles and symmetry are refined to within microns. A round brilliant has 58 facets — and if even one angle is off, light leaks out and the brilliance dulls. The optical symmetry achieved here is the true source of brilliance (white light) and fire (the flashes of rainbow color).

5. Inspection

The finished stone is rigorously examined under loupe and microscope. Only when its proportions and symmetry meet exacting standards does it emerge as a finished gem. Brands chasing the highest quality repeat this inspection again and again, allowing no compromise.

It Is the Artisan's Skill That Unlocks Maximum Brilliance

A single diamond passes through the hands of many skilled craftspeople, from planning to final polish. Workshops pursuing the pinnacle of quality may divide the process into even more specialized steps, each handled by a dedicated expert. Two stones from identical D-color rough can shine differently depending on this precision — which is exactly why a diamond is worth choosing with an understanding of how it was cut.

ADAMAS: The Beauty of a Perfectly Polished Stone

At ADAMAS, we work exclusively with K18 gold and D-color diamonds, selecting only stones polished to true optical symmetry. Once you know the long journey from rough to gem, the light dancing at your fingertips feels all the more precious. For timeless, unchanging beauty meant to be passed down through generations, discover the stone that is right for you at the ADAMAS official site.