Adult (above) and immature (below)
Bill color was actually more pinkish, as in the image below.

Description Chloridops kona (Wils.) (above) adult (below) immature
Date 1893-1900
Source Walter Rothschild: The Avifauna of Laysan and the neighbouring islands with a complete history to date of the birds of the Hawaiian possession. R.H.Porter, London. http://www.sil.si.edu/digitalcollections/nhrarebooks/rothschild/CF/index.cfm
Author John Gerrard Keulemans (1842–1912)
Source: https://commons.wikimedia.org/wiki/File:Chloridops_kona.jpg

The Kona grosbeak (Chloridops kona) is an extinct species of Hawaiian honeycreeper. The Kona grosbeak was endemic to the Kona District on the island of Hawaii. Order: Passeriformes, Family: Fringillidae, Subfamily: Carduelinae, Species: Chloridops kona (S.B.Wilson, 1888), Synonyms: Psittirostra kona (Wilson, 1888)