The natural dye recognition is more experience through comparisons. However, it has to do with depth of colour, clarity of colour and always remember that it is almost impossible to get acidic shades with natural dyes. But the other factor is the wool itself. If it is machine spun then you don't get the same clarity and depth as you would with handspun. The machine spun take traces of grease from the machine which will then make dying more difficult and the dye will not have the same clarity. To me the wool in your pieces are not naturally dyed. Having said that it is not that easy to tell from photos ( not for me anyway). However, the later version of the Chobis were at best a mixture of natural and chemical dyes. It does take longer to dye wool with natural dyes and it is harder work, which not all producers want to go through. Time is money and all that. So they use a mixture.

It really depends but at best the red is a mixture. The Chobis are usually washed to death and an abrush or change in colour is not necessarily an indication of vegetable dying if that is what you are suggesting

Thanks for the info. I assumed they would not be natural dyes, based on price alone.