I don’t usually cut material that valuable 🙂
For quartz angles, cutting the breaks to CP first loses about .024*width in pavilion height, or 0.24mm for a 10mm stone. This will vary somewhat if you change the angles. As Long & Steele suggests, you can stop a bit short of cutting to CP. If you cut a level girdle, it will work out. For a beginner, the meetpoint method is easier, and the material loss is small.