With a name derived from the Greek for “gift from the sun”, the varietal name heliodor is used interchangeably with that of golden beryl when referring to greenish-yellow to golden-yellow beryls. These hues are caused by the presence of ferric iron impurities within the mineral’s internal crystal structure, which differ chemically from the ferrous iron ions that are responsible for the light blue coloration in aquamarine.

However, these two iron-containing beryl varieties can be transformed into one another upon exposure to heat (heliodor to aquamarine) or irradiation (aquamarine to heliodor), with the former process being more commonly employed due to the aquamarine’s superior salability and higher value. As a result, most of the enhanced bright yellow material encountered within the marketplace has been instead produced via the irradiation of colorless goshenite beryl, which is fairly inexpensive in its original form.