Various shades of purple are achieved by dyeing with Logwood powder and/or Extract. Overdyeing with an Iron solution turns the fabric grey-ish purple. Different fabrics and how 'exhausted' the vat is yields variations of colour.
Fading over time is natural but avoid bleach, anything acidic and direct sunlight to keep your colours a long time. Machine washable (mild detergent and cold water is best.)
Also note: Colours may appear slightly different in these photos and on your computer screen that the real thing.