Natural indigo is the blue dye extracted from the leaves of the Indigofera plant.
The color of natural indigo is deep and rich. See this book for a complete history of natural indigo.
It is different than artificial indigo (anilin) which chemical-based and toxic.
I found these shirts dyed with natural indigo:
- Indigo Dyed Long Sleeve Shirt by NinoshkaIndia — $50
- Indigo Dyed Crewneck Shirt by FairIndigo – $43
- Indigo Dyed Henley Shirt by FairIndigo – $55
- Natural Indigo Dyed Shirt by Goodlife — $73 USD
- Indigo Dyed Crewneck Sweatshirt by Tonn — €100.00 or $110 USD
- Men’s Indigo Shirt by Mae Teeta — 3,900.00 ฿ or $125 USD
- Men’s Shibori T-Shirt by T. J. Indigo — $85 USD