The clear distinction between a pink sapphire and a ruby can be quite complex in individual cases. Where is the boundary between a ruby and a pink sapphire? The world's leading gemological laboratories have published a lot about this and have partially harmonized in their decision. A clear demarcation is complex and an individual assessment for each stone. The ruby and sapphire are closely related. Both are varieties of the mineral corundum and share the chemical formula aluminum oxide. The decisive factor is the color saturation of the red component.
‍

What is the color cause of ruby?

Rubies and pink sapphires get their color from tiny admixtures of trace elements that are incorporated into the crystal lattice and can affect hue and saturation of color. The trace element chromium gives ruby its characteristic red color, and chromium concentration affects the ruby's color intensity. In addition, chromium causes red fluorescence, making rubies with strong fluorescence appear more luminous. If the trace element iron was present in the ruby's growing environment, the stone may have darker hues, sometimes brownish or bluish, as well as lower fluorescence.

‍

What are the shades of rubies and what is the difference between ruby and pink sapphire?

The hue of rubies can range from strong purple to intense red to an orange-red. Its tone can be medium to dark with vivid saturation or low saturation with dark tones. If the chromium-generated color saturation is not sufficient to create a red color perception, the stone appears pink and thus becomes a pink sapphire. If orange or violet hues predominate, it can also be classified as a fancy sapphire. Traditionally, the color scheme is always interpreted somewhat more broadly in the countries of origin. Here in Europe and America, however, one is very precise and reliable, as it influences the value significantly. So it can happen that in Asia or Africa a ruby is unearthed, which on its journey becomes a pink sapphire.

‍

Are there standards for distinguishing rubies from pink sapphires?

The world's leading gemological institutes have attempted to create standards by which the identity of a stone can be determined. To be called a ruby, the body color must be red. Reference stones are used in laboratories to precisely define a reliable color scheme for the ruby, and each stone is categorized in the same light and at the same viewing angle. The chemical analysis of chromium concentration alone is not conclusive, as color perception is also significantly influenced by the size and cut of the stone. There can be differences between laboratories, but the leading laboratories have harmonized here to give a comparable assessment. Thus, it requires a great deal of expertise and an experienced eye, which is why one should only place one's trust in an internationally recognized laboratory for fine ruby qualities, as the value of a bright "pigeon blood red" ruby is several times higher compared to an intensely pink "hot pink" sapphire of comparable size, transparency and purity.

‍

‍