[2] Metzler Rebecca A, Abrecht Mike, Olabisi Ronke M, et al. Physical Review Letters, 2007, 98(26): 268102.
[3] Brink D J, Vander berg N G, Botha A J. Appl. Opt., 2002, 41: 717.
[4] Towe Kenneth M, Harper Jr Charles W. Science, New Series, 1966, 154(3745): 153.
[5] Alexander A, Sherwood H. Gemmologist, 1940, 10: 48.
[7] Tan T L, Wong D, Lee P. Opt. Express, 2004, 12(20): 4847.