Every language on the left-hand road says this fruit with an n in front: nāraṅga, nārang, nāranj, Spanish naranja, right up until Italian, where it vanishes. It did not wear away. The usual explanation is a new article boundary: a proposed una narancia became un’arancia. The intermediate is reconstructed.

• English does this too, in both directions. A napron became an apron and a nadder became an adder; going the other way, an ewt became a newt and an eke-name (an “also-name”) became a nickname. Linguists call it rebracketing. It is one of the few sound changes you can watch happen in your own mouth.
• The right-hand road is the same fruit under a different name. The bitter orange came overland with Arabic and kept its Sanskrit name. Portuguese trade supplied another set of names for the sweet orange. Those words need their own attestation dates. Modern Arabic ended up with both words, one for each fruit.
• The color name comes from the fruit. The OED records orenge colour in 1512, as cited by Wordorigins. The standalone color name is later.
• A solid line is a borrowing, where the word changed hands between languages. A dotted line is a change of meaning inside one language. The crossed-out narancia is a reconstructed intermediate, not a dated attestation.

The rebracketing account of the lost n is the standard one and is still hedged in the sources: Etymonline says “probably.” The Sanskrit word is itself thought to be a loan, most likely from Dravidian, and its deeper origin remains uncertain.

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Dates follow the earliest cited evidence for the form and sense shown. Notes name the sources. Timeline spacing is compressed; undated stages are placed in sequence.