Colour investigation:Topaz

Imperial topaz is yellow, pink or pink-orange and is the most valuable of the topaz colours Impurities of trace elements and structural defects can contribute to the colour in topaz; chromium as a replacement for aluminium is the colouring element for red and pink topaz As with many popular gems, topaz is treated to improve its colour; in its natural state topaz is yellow to brown.

The only official variety of topaz is Imperial topaz which is the most valuable Rutilated topaz - similar to rutilated quartz but the inclusions of "Rutile" in topaz are actually limonite, not rutile Since topaz comes in many colours, the birthday choice colours are numerous.

The variety of colours, good hardness, transparency, and abundance make topaz a popular choice for jewellery. . Source