Topaz is the best and cheaper substitute for Yellow Sapphire (Pokhraj). This is never adverse.

• Name : Hindi : Sunela.
• Gem-Group : Quartz.
• Crystal Structure : Trigonal.
• Composition : Silicon Dioxide, SiO2.
• Hardness : 7
• Planet : Jupiter ( Guru ).
• Availability : Brazil, Spain, U.S.S.R, INDIA.
• Specific Gravity : 2.65
• Refractive Index : 1.54-1.55
• Double Refraction :  0.009
• Lustre : Vitreous.
• Process : Same process like Yellow Sapphire ( Pokhraj ).