so recently i got a few Nd:GdCOB crystals with hr and oc mirrors coated on the crystal. Nd:GdCOB is a very interesting crystal as it is self frequency doubling so it doesn't need an intracavity doubling crystal. also it can be very efficient (up to 20 percent efficient from what ive read). my crystal lases at 545nm when pumped with a 300mw 808nm diode but ive heard that with the right hr and oc mirrors, you can get it to lase at 532nm. i have a few of these crystals to mess around with and ill try to pump it with a 796nm diode instead of 808nm diode (ive read that using a 796nm diode to pump the crystals is more efficient than 808nm.) i think that it also might be the same crystal as the one in those lasence 545nm modules i bought some time ago as they use a 808nm pump diode. also if you want one. ill be happy to sell you one, just look at my post on the bst section.