I’m certain that the detail shown below refers to indigo – sold by the block, stitched into a cloth cover – and that below the block is a piece of indigo-dyed fabric.
The term for indigo is either ‘indigo’ or a word containing the element ‘nil’ most languages, though Chinese and some south-east Asian languages have a distinct term for it. With my previous post mentioning Jews in Thailand, and Thai being one of those exceptions, I’ll pause to consider its alphabet. (In Thai, Indigo is Khrām).
It isn’t difficult to render the last few characters (in the inscription below the cloth) as t ‘khram’ in Old Thai : all you need do is suppose the Voynich ‘o’ should be part of the letter to its right.
The Thai alphabet with phonetic rendering (See too Ancient Scripts.com).
The first known example of Thai script is 1283 AD – which doesn’t especially please me; evidence for Jewish traders which was given in my previous post refers to the tenth century. However, in this context, see ‘Jews in China‘
The late thirteenth century does coincide with Roger Bacon’s time (c. 1214–1294) and is less than fifty years before we hear of a small Genoese community established in the Chinese port of Zaytun or Guangzhou.
There, in the ninth century, all resident foreigners had been massacred: as many as two hundred thousand, according to the Sirafi, Abu Zayd Hasann. Jewish merchants had been among them and Muslim Arabs, Muslim Persians, Zoroastrians (i.e. Parsees or Mazdaians) and Christians.
 – mentioned in 1326 by André de Pérouse.
But the script used for Voynichese is tantalising in the number of scripts it does seem to resemble somewhat.