Yttrium Aluminum Garnet 

(YAG, Y3Al5O12)

Certain unique garnets can be grown for specialized applications using a hydrothermal approach. Customers may require specialty crystals that are less successfully grown using classical CZ pulling methods. These unusual materials include Sm coated Nd:YAG for ASE suppression, Tb doped garnets, various LuAG compositions and many others. 

See references for some possibilities.

“Hydrothermal Growth of Single Crystals of Lu3Al5O12 (LuAG) and its Doped Analogs” C. Moore, C.D. McMillen, J.W. Kolis Crystal Growth and Design, 2013, 13, 2298-2306

“Revisiting the Hydrothermal Crystal Growth of YAG” C.D. McMillen, J.M. Mann, J.Y. Fan. L. Zhu, J.W. Kolis  J. Crystal Growth 2012, 356, 58-67.

“Hydrothermal Crystal Growth and Epitaxy in Garnet Systems” C. McMillen, C. Moore, J. Kolis, in Advances in Optical Materials (AIOM), OSA Technical Digest 2012 paper IW5D.2.