Natural rubies often show central grayish blue cores in their untreated state, which are usually considered to be of a low quality. Therefore, most rubies are artificially heat-treated at high temperatures to improve the color. During the heating process, the flux accompanied by the process is cooled down and becomes amorphous residues that remain in the fractures or surface cavities of ruby unintentionally, and thus the clarity and transparency of the ruby, to some extent, are enhanced. Subsequently rubies that have experienced the heat treatment are often identified as those with traditional filling treatment, by which the original thoughts of merely conducting artificial enhancement are misunderstood and the values of the rubies are influenced. This paper intends to remove the amorphous residues in the ruby on the experimental basis so as to reassign it to the acceptable range of pure heat enhancement, and in this way the appropriate value of the ruby could be shown on the gem market. The amorphous residues existent in natural rubies due to heat enhancement and treatment are cleared by immersing the rubies in the hydrofluoric acid (HF) with the concentration of 23% in which the glass residues that remain in the fractures and pits of ruby are readily dissolved so as to attain the goal of clearing. ICP-AES analysis of the hydrofluoric acid solution with the amorphous residue solute mentioned above was used to indicate the concentration of Si and Al, namely 28.60 μg/mL and 2.795 μg/mL respectively, by which the weight of the removed residues was roughly calculated so that the filling degree of the amorphous residues that unintentionally added to the ruby could be determined. Fourier transform infrared spectra of ruby specimens were determined before and after the clearing process for comparison. The infrared spectra of ruby prior to the clearing process showed that, in the range of 1 100～1 000 cm^-1, the ruby exhibited broad band positioned at 1 050 cm^-1 due to the unsymmetrical stretching vibration of ν_as (Si—O—Si), which indicated that the residues were amorphous. A sharp band centered at 744 cm^-1 in the 750～600 cm^-1 region corresponded to symmetrical stretching vibration of ν_s (Si—O—Si), whereas none of the characteristic Si—O vibrations caused by amorphous residues was detected by the infrared spectroscopy after the acid treatment of the ruby, and only a broad band in the range of 950～600 cm^-1 featured at 736 cm^-1 and 622 cm^-1 was shown, which was caused by the Al—O fundamental frequencies of corundum and thus displayed the characteristics of crystallized metal oxide, suggesting that the amorphous substances in ruby were removed thoroughly and ruby specimens eventually fell into the pure heat-treatment (enhancement) category rather than the glass filling treatment category. After the performance of clearing experiments on the ruby specimens, the fractures and pits on the surface of the rubies which had previously been covered by amorphous residues were clearly visible under the gemological microscope.