romanillos2002, p. 350: In an inventory made in 1564 of Princess Juana of Austria’s musical instruments there was a vihuela with a back of alternating Brasil wood and white [wood strips], ebony sides and with the name Don Diego de Rojas written between the pegs. It was valued at 8 reales equivalent to 272 maravedies (una biguela, las espaldas quarteadas de madera de Brasil y blanca y el cerco de hebano, que entre las clavijas tienen escripto Don Diego de Rojas, tasada en ocho reales, que valen doscientos y setenta y dos mrs). Source moll1965.
Romanillos is mistaken about the date of the inventory that mentions this vihuela, given that the princess died in 1573. Moll’s article is not very clear about the date.
There is no evidence of a violero named Diego de Rojas, and moreover with the title “don” it is more likely to pertain to an owner. The two candidates identified so far are both conquistadors who spent a great part of their lives in the Americas:
1) Diego de Rojas (1500-1544), see https://es.wikipedia.org/wiki/Diego_de_Rojas
2) Diego de Rojas (1522-1598), https://www.geni.com/people/Diego-de-Rojas/4317790933580054651