BACKGROUND There are water molecules and hydrous mineral inclusions in natural ruby and sapphire. The hydrous minerals disappear easily after heat treatment, which causes the physical and chemical properties of ruby and sapphire to change. Thus the hydrous mineral inclusions have important indications for identifying whether or not ruby and sapphire have been heated. OBJECTIVES To analyze the characteristics of the hydrous mineral inclusions, and discuss the validity of the identification method for identifying whether or not ruby and sapphire have been heated through hydrous mineral inclusions. METHODS Mineral inclusions were characterized by the gem microscope, infrared spectroscopy and microscopic confocal laser Raman spectroscopy. RESULTS The hydrous mineral inclusions showed good shape and clear appearance. The infrared spectrum characteristics showed diaspore characteristic absorption peaks at 2105-2110cm-1 and 1977-1985cm-1, and kaolinite peaks at 3619cm-1 and 3696cm-1. The microscopic confocal laser Raman spectroscopy analysis showed the typical characteristic peaks of hydrous mineral inclusions such as amphibole, mica, apatite and feldspar. CONCLUSIONS The features shown in the results reveal the water-containing characteristics of ruby and sapphire samples, which can be used to determine the natural rubies and sapphires without heat treatment.

On the basis of lab researches performed in 2009 for the gemmological properties and compositions of peripheral materials of the red of Tibet,the investigation team of National Gemstone Testing Center,China(NGTC) performed a field investigation on occurrence of international disputing about red of Tibet from the geology,mineral deposit,stratigraphy and geomorphology at the border area between Bailang county and Jiangzi county in Shigatse,Tibet(E29°04′01.5″,N89°20′54.8″) in May,2010.The investigation team interviewed the villagers of Mencuo and Zhalin villages,viewed the trade process and collected the red feldspar samples.The results show that the majority of red feldspar samples in the field were artificially placed on the ground surface and in the loose ground,which supports the previous deduction of lab researches in 2009.

An in-situ Raman spectra test and study on the hemimorphite were carried out by high temperature Raman spectra technique.The test results show that the characteristic Raman peak of 3,470 cm-1 representing O-H stretching vibration in the molecular H2O is disappeared as the hemimorphite being heated 800 K,but the characteristic peak 926 cm-1 marked Q1 of the main framework [Si2O7] is been retained,which means the structure of the hemimorphite is not changed as the H2O lost.The characteristic peak of 3,580 cm-1 related to stretching vibration of the O-H in the structure water(OH) is disappeared as the sample being heated 1,050 K.The relative intensity of the characteristic peak 926 cm-1 related to symmetric stretching vibration of non-bridging oxygen of structure unit Q1 gradually decreases,comparing with the growing Raman band of Q0 characteristic peak at 852.4 cm-1,which indicates the phase transformation of the hemimorphite is started out at 1,050 K.The structure water(OH) is dehydrated completely as the temperature is over 1,100 K,the characteristic peak(3,580 cm-1) of the structure water(OH) disappears completely,the characteristic peak related to Si-Onb stretching vibration becomes 855 cm-1,which shows that primary Q1 of the hemimorphite is returned to Q0(i.e.\),and which means that the hemimorphite is completely transformed to willemite.