Cost is a major factor in deciding between the two. A ruby (or sapphire) orifice costs in the $15-20 range. These orifices can last anywhere from 0 – 40 hours. If proper break-in procedures are not used, a ruby orifice could fail the first time you turn high pressure water on. Following the WARDJet recommended break-in procedure can help you to avoid orifice failure . Unfortunately, even with proper break-in, the life of a ruby orifice is highly variable.

Currently, diamonds cost around $425. With proper water quality and a thimble filter installed at the cutting head, diamonds are guaranteed to last for at least 600 hours. The thimble filter is a very small, very fine filter that is located above the orifice to trap any debris before it gets to the diamond orifice.

Reasons to Choose a Diamond Orifice:

Because of their long life, diamonds offer a major benefit when cutting long-running jobs, especially those out of very expensive materials. For instance, a 6" thick Inconel part that takes 20 hours to cut would probably be a poor candidate for a ruby orifice that could potentially fail before the cutting program is complete.

When cutting with multiple cutting heads, diamonds are a benefit because you can plan to change them all out at one time, once or twice a year (depending upon usage). Just imagine trying to cut with 4 cutting heads equipped with ruby orifices - the ruby in head one lasts 19 hours, the ruby in head 2 lasts for 24.7 hours, the ruby in head 3 lasts 12.5 hours and the ruby in head 4 lasts 43 hours. You can either change all 4 out when the first one fails or you will end up changing an orifice every couple of hours.

Stream quality with a diamond is better than ruby or sapphires, and as a result, cut quality is smoother.

Reasons to Choose a Ruby Orifice:

If none of the benefits of diamonds listed above applies to you or if you are frequently changing nozzle/orifice combinations, you may find it better to stick with rubies. In a “job shop” or short-run environment, rubies may be a better choice because every time you take the cutting head off the machine to change the orifice/nozzle combination, you increase the risk of debris getting to the orifice that could cause damage. Also, every time the operator changes the orifice, there is a chance that it may accidentally drop in the waterjet tank. (NOTE: always change the orifice and nozzle away from the machine to avoid this.) Dropping a $20 ruby orifice in the tank, while unfortunate, is not heart breaking. Conversely, dropping a $425 diamond orifice in the tank would drastically impact your potential profits on a job.