Single crystal stishovite was grown in the high pressure apparatus. Its quality was checked by X ray, FTIR, and EPMA techniques. Crystal orientation was determined by precession camera. It was shaped to a rectangle with 200-500 micron meters. By detecting 20 peaks in high frequency resonance ultrasound spectroscopy, crystal elastic constants were determined. Porosity effect was systematically analyzed by using the buffer layer model in FEM analysis. The result was formulated as an elegant function of Poisson ratio, asperity, and porosity.