Digging into "naranja" (the Spanish name) this article claims that the jump to the french included a latin "golden" component to it (aurum), thus forming "orange". In fact "Citrus Aurantium" is a type of orange.
http://etimologias.dechile.net/?naranja
It also claims that the jump to arancia in Italian comes from the portuguese laranja, losing the "l" as it seems "la arancia".
Finally, tangerine (after Tanger) is called mandarinas (after China) in Spanish, which has been for the longest time a source of confusion for me.