A number of factors enter into the performance of a diamond wheel dresser. Each is important, but particularly with single and multiple point tools, there's nothing more important than the diamond itself. They are the hardest naturally occurring substance. While diamonds consist of pure carbon, their shape and quality can vary enormously, and each variant has it's own effect on tool performance and economy.
Quality: Among naturally formed diamonds, all but the most expensive, gem quality stones will have flaws. These can be evidenced as slight discolorations, which only rarely affect the performance of the diamond, or they can be seen as cracks and fissures. Whether located near the stone's surface or deep in its core, even the slightest cracks can cause poor performance and premature failure.

Shape: Diamonds come in a variety of shapes, and provide from one to six usable points. A usable point is one with sufficient height and sharpness for proper performance that will not fracture during operation. With six such points, the stone can be rotated up to five times, each time exposing a new point.

Stones with a higher number of usable points have a higher initial cost. With proper use and periodic point rotation, however, the higher initial cost is rewarded with longer tool life and eventually greater economy.

Diamond Dressing Tool Stones Normal Size and Tolerance
Carat Decimal Tolerance
1/5 .20 (.17 ~ .23)
1/4 .25 (.21 ~ .29)
1/3 .33 (.29 ~ .39)
1/2 .50 (.40 ~ .62)
3/4 .75 (.63 ~ .87)
1 1.00 (.88 ~ 1.14)
1 1/4 1.25 (1.15 ~ 1.34)
1 1/2 1.50 (1.35 ~ 1.74)
2 2.00 (1.75 ~ 2.25)
Hover over the links for details of various shapes



Elongated Tool Stone



Shape and Quality Classification
Grade Description
#2 Gem Sound, smooth dodecahedrons with no detrimental cracks or flaws
#3 Ultra Sound stones, predominately octahedral, with no major cracks or flaws
#4 Premium Sound, semi-blocky and octahedral stones with smooth, frosted or slightly irregular surfaces, having 3 or more points and no major cracks or flaws
#5 AAA Semi-blocky, octahedron and dodecahedron stones with at least 3 usable points
#5 AA Semi-blocky and irregular shapes with 1 or 2 good points
#5 A Irregular shaped stones with 1 good point
#6 B (Tool room) Possibly resettable stone, rough surface, with 1 good point
#7 TA (Throw away) Disposable non-resettable stone
How to Determine Diamond Size

Wheel Diameter Wheel  Width Recommended Size in Carat Hardness: Although all diamonds are chemically identical, differences in hardness do occur. Stones mined in Africa, for example, tend to be hardest. These are followed closely by stones from Russia, Australia and Brazil. In terms of color, white or yellow diamonds tend to be the hardest.
100 12 0.25
150 12 0.30
175 12 0.50
250 40 0.75
350 30 1.00
400 30 1.25 Size: Larger diamonds are needed for larger wheels. As a rule of thumb, we recommend selecting the largest diamond your budget can afford; and as a minimum, at least a half carat for every inch of wheel face. Other factors influence the selection of a diamond's size.

These include:
Wheel diameter
Rrigidity of the machine or dressing device

Use of coolants
Grain coarseness
Bond hardness
Dressing wheel speeds

Larger stones offer several advantages. First, with more of the stone contacting the wheel, the dressing operation is completed faster. Second, with greater surface area, heat is dissipated more rapidly. Third, larger stones are studier, and can withstand more abusive conditions. And finally, they last longer.
450 50 1.75
600 50 2.00
600 75 2.50
750 75 3.00
750 100 3.50
A diamond should be large enough such that it's surface area is sufficient to give all detrimental heat to its surrounding holder. Any built-up heat may lead to the destruction of the diamond. Diamond size is given in carat (1 carat=0.2g).