The original reference point for the citrine colour was the citron fruit. The first recorded use of citrine as a colour in English was in 1386. It was borrowed from a medieval Latin and classical Latin word with the same meaning. In late medieval and early modern English the citrine colour-name was applied in a wider variety of contexts than it is today and could be "reddish or brownish yellow; or orange; or amber (distinguished from yellow)". In today's English citrine as a colour is mostly confined to the contexts of (1) gemstones, including quartz, and (2) some animal and plant names. E.g., Motacilla citreola is the scientific Latin name for a certain wagtail bird that lives in Asia and has golden-yellow plumage and the bird may be called the "Citrine Wagtail" in English.
^The colour displayed in the colour box above matches the colour called citrine in the 1930 book by Maerz and Paul A Dictionary of Color New York:1930 McGraw-Hill; the colour citrine is displayed on page 51, Plate 14, Color Sample L6.
^Maerz and Paul A Dictionary of Color New York:1930 McGraw-Hill--Discussion of the color Citrine Page 154
^Maerz and Paul A Dictionary of Color New York:1930 McGraw-Hill Page 193; Color Sample of Citrine: Page 51 Plate 14 Color Sample L6 (The colour identified as "Citrine" in this colour sample matches the colour in the colour display above.)