A go-with-all multi-colored necklace with natural precious gemstones, duly certified from International Gemological Institute And Testing Laboratory.
Sapphire is a gemstone, a variety of the mineral corundum, an aluminium oxide (α-Al2O3). It is typically blue in color, but natural "fancy" sapphires also occur in yellow, purple, orange, and green colors. The only color which sapphire cannot be is red - as red colored corundum is called ruby, another corundum variety.
Note: These are all natural gemstones, dug from deep under sea or earth, long after they have gone through a lot of chemical changes. Hence, it's natural that these stones have inclusions inside the stone. They can be black spots, dark included crystals (DINX), included crystals (INX), feathers, pinpoints etc at different locations. Thus, if you have bought a stone which is absolutely crystal clear or without any inclusions, then please get it checked as it can be semi-precious or synthetic, since crystal clear natural stones like emerald / yellow sapphire / blue sapphire / ruby will be exorbitantly expensive.