Gemmological and Spectral Characteristics of Corallium sp. nov. from Midway Island

12 pieces of Corallium sp. nov. were collected and studied by conventional gemmological testing methods and advanced instruments including XRD, LA-ICP-MS, FTIR, Raman spectrometer, and UV-Visible light spectrophotometer. A comparative study was conducted on 11 samples of traditional gem-quality coral species (such as Paracorallium japonicum, Corallium elatius and Corallium rubrum). The results showed the conventional gemmological characteristics and the mineral components of Corallium sp. nov. are almost the same as those of traditional gem-quality coral except that the colour of the Corallium sp. nov. is usually pale pink to salmon with uneven distribution of orange-red patches. The infrared spectra of Corallium sp. nov. showed the absorption peaks located near 1 423, 879, 706 cm^-1, while the Raman spectra mainly appeared in 277, 711, 1 086, 1 014, 1 127, 1 297, 1 518, 2 150, 2 255, 2 538, 2 640, 3 040, 3 374, 3 748 cm^-1, and the UV-Visible light spectra were mainly absorbed at 283, 313, 493 nm and 525 nm, which were basically consistent with the spectral characteristics of other traditional gem-quatity coral species. The trace elements content of Corallium sp. nov. is characterized by low Mg content and high Ba content. The binary diagram was drawn with Mg/Ca and Ba/Ca ratios as components, which can clearly distinguish Corallium sp. nov. from the other traditional gem-quality coral species.