Element identification of different gemstones by using LIBS-PCA method by Mohamad Saufi, Noradilah, Adnan, Nurul Nadia, Rizvi, Syed Zuhaib Haider, Roslan, Mohd. Sufi, Razak, Siti Norazida, Hasim, Nurhafizah, Mansor, Nurin Iffah