High quality bonding of undoped yttrium aluminum garnet (YAG) and Neodymium doped YAG (Nd:YAG) single crystals is critical for thermally and mechanically robust composite high power solid state laser designs. The optical properties of composite crystals must not be significantly diminished compared to monolithic single crystals. Necessary surface preparations for optical quality bonds, and methods to measure surfaces including atomic force microscopy (AFM) were examined. The optical characteristics of composites with one or more bond interfaces in high power solid state laser (HPSSL) slab or test coupon form were analyzed. Select insertion loss, stress birefringence, transmitted wavefront distortion, and optical microscopy results will be shown. High bond mechanical strengths were verified using thermal shock and 4-point flexure tests. The flexure test results were analyzed using Weibull statistics and fractography, illustrating the medium-high to high energy failures typically observed in bonded YAG sets with characteristic strengths (≥445MPa), higher than those of a commercially available YAG bond (351 MPa) and as-grown YAG crystals (409 MPa) with no post growth anneal. Acid etching generally tightened strength distributions, but with similar decrease in measured strengths for both monolithic YAG and bonded YAG sets. Recent efforts in bonding ceramic YAG and Nd:YAG slabs are briefly summarized.