I just checked my APs... all sapphire
ROO T3 - sapphire
ROO EOD - sapphire (Uwe double AR)
ROO Tour Auto - sapphire (Uwe double AR)
ROO Juan Pablo Montoya - sapphire (? single AR, specified by multiple TDs)
ROO Survivor - sapphire (Vac double AR)
ROO Grand Prix - sapphire (Vac double AR)
ROO Chronopassion - sapphire (Ryan double AR)
Diver V4.1 - sapphire (single AR)
Diver V5 - sapphire (single AR)
ROO Rubens Barrichello II - currently with Vac for service/AR, so cannot check right now
I had a Safari and Rubberclad (which had an AR crystal) too but have sold them, so cannot test. Eventually I will probably part with the Tour Auto and Chronopassion too. I really favor the special editions... Besides liking bad ass watches, I find them more accurate as the major rep flaws (i.e. date window position and coplanar alignment of crown/pushers) are evident to a great degree on the standard ROO models.
The 'tap test' does seem to work. I tried it on my two Flyback PAMs, a 253I with dome mineral glass and 332L with dome sapphire glass. There was an obvious difference in sound, with the mineral glass having a high pitch, hollow overtone not present in the sapphire crystal.
I did not bother with the water test, as I figured the AR coatings on many of my ROOs might interfere with the surface tension of the crystal material.
Only surprise I found regarding mineral instead of the specified sapphire crystal is a VCO Deep Stream, an inexpensive rep ~ $250. The crystal is very clear and doesn't have any scratches, but it has the high frequency overtone. It was specified as sapphire in the TD description.
There is also a large variation in quality of the sapphire crystals as others have pointed out... clarity of most rep crystals is far short of the BigMatt C3 Corundum in my 5218-202/A, or the gen crystals in my Sinn 903 H4, Tudor Heritage, Seiko Spring Drive SPS001, and Paul Picot Technicum. I thought the sapphire crystal in my PAM305 was terrible, but having Vac recoat it made it much, much better; the crappy AR was to blame more than the crystal itself. The best AR coatings I are those from Chieftang and K222, unfortunately I don't think either are doing it anymore and both are quite fragile and susceptible to scratches. The coatings from Vac and Uwe are not quite as good but as much more durable. I have one of Ryan's AP ROO crystals which seems phenomenal, it is in my Chronopassion V5.
One final point - there are at least three different crystal sizes used in the various AP ROOs. The RBII crystal is about 32mm; the GP crystal is about 33mm, same as HBB; the other ROOs and Divers are about 32.5mm. There are differences in bevels too. For those that have GPs and want AR without spending ~ $135 and waiting several weeks for recoating, pick up a HBB crystal! V1 or V5 are best being colorless, most of the V6 crystals have noticeable blue.