CVD single crystal diamond is typically grown using methane and hydrogen as precursors under high temperature (approximately 1000°C), atmospheric pressure (1 atm), or low-pressure conditions. The growth occurs via vapor-phase epitaxy on a single crystal diamond substrate, which can be natural diamond, HPHT diamond, or CVD diamond. This method enables the production of high-purity, large-size diamond single crystals. JCB offers CVD rough diamonds in D-E-F-G-H colors, with specific colors customizable according to customer requirements. The clarity ranges from VVS to VS, and the current growth size is 3.0 carats to 30 carats per stone.
| rough diamond size (mm) | rough diamond weight (ct/piece) | Cut-able Loose Diamond Size |
| 7 x7x4. 0-4.4 | 3.5-4.0 | 1ct circle |
| 8 x8x4. 6-5.0 | 5.2-5.6 | 1.5ct round |
| 9 x9x5. 1-5.5 | 7.2-7.9 | 2ct circle |
| 10 x10x5. 7-6.2 | 10.5-11.5 | 3ct circle |
| 11 x11x6. 5-7.0 | 14-15.5 - | 4ct circle |
| 12 x12x7. 5 | 19-21 | 5ct circle |
| 13 x13x7. 5 | 23 to 25 | 6ct circular |
| 12 x9. 5 x6. 0 | 11-12 | 3ct ellipse 5ct Emerald |
| 12 x10x6. 0 | 12-13 | 3ct ellipse 5.5ct Emerald |
| 13 x11x6. 5 | 16 and 17 | 4ct oval 7ct Emerald |
| 15 x12x7. 0 | 20-23 | 6ct ellipse 10ct Emerald |
