Blåt rav er dannet fra harpiks ligesom normalt rav.
Den flotte blå eller grønblå farve skyldes fluorescens, men kun i naturligt sollys med UV-lys. Blåt rav kan komme fra:
- ^ L. Linati and D. Sacchi, V. Bellani, E. Giulotto (2005). "The origin of the blue fluorescence in Dominican amber". J. Appl. Phys. 97, 016101. doi:10.1063/1.1829395.
- ^ a b Paywalled: Gems and Gemology 50(2) July 2014: Color Phenomena of Blue Amber Citat: "...The greenish blue color observed in some amber from the Dominican Republic and Indonesia is actually fluorescence stimulated by ultraviolet (UV) light...The amber from this study also showed the Usambara effect, the phenomenon in which color varies with the path length of light through a sample...", backup
- ^ a b geologyin.com: What Causes the Color Phenomena of Blue Amber? Citat: "...The greenish blue color observed in some amber from the Dominican Republic and Indonesia is actually fluorescence stimulated by ultraviolet (UV) light...Hydrocarbons in the blue amber shift the sun's ultraviolet light down in frequency, resulting in the glow of blue amber...This effect is only possible in some specimens of Dominican amber category, in some Mexican ambers from Chiapas and some ambers from Indonesia. Any other amber (such as Baltic amber) will not display this phenomenon, because its original resin is not from the Hymenaea protera tree... Although there are several theories about the origin of Dominican blue amber, there is a great probability that it owes its existence to ingredients such as anthracene as a result of 'incomplete combustion' due to forest fires among the extinct species Hymenaea protera trees about 25 to 40 million years ago...", backup