It doesn’t say on <a href="">wikipedia</a> if it can be used for making dyes, but the colour is due to light exposure…
Young fruit bodies that are still beneath the earth are white; as they mature and emerge from the ground, the exposure to light causes the color to change to violet
and also
It was one of six species that appeared as part of a series depicting native New Zealand fungi on stamps, released in 2002
It is incredibly striking, so I can see why it was ‘honoured’ with a stamp