Q: Do you recommend crystal or diamond tip microdermabrasion? Or are they both good options?
A: I've done both for clients, and I think it depends. Any type of real microderm (as opposed to the scrubs that call themselves microderm) will be highly abrasive and therefore a calculated risk--it's using a variably pro-inflammatory treatment to yield a positive result--however in my experience, traditional crystal microderm is both harsher and more effective, meaning it can (not necessarily will) have more intense inflammatory side effects like redness, dryness and increased sensitivity, but it also will give faster results for textural problems.
Diamond tip, on the other hand, is much more versatile, because you can easily switch between different grits, down to very fine. That makes it a good option for more sensitive skin, for frequent combination with chemical exfoliants in a series (not uncommon to do sessions fairly close together to reduce acne scars, for example), and to switch between finer and coarser grits on different areas that have different needs (face vs body, cheeks vs undereyes, etc.). From a professional standpoint, diamond tip is waaaaay more convenient, because you don't have to clean up all of those damned crystals and there's less likelihood of peeling after (esp when combined with another form of exfoliation), but again, traditional is going to yield faster results in my experience.