And a certain woman named Lydia, a seller of purple, of the city of Thyatira, which worshipped God, heard [us]: whose heart the Lord opened, that she attended unto the things which were spoken of Paul. Acts 16:14
[Lydia would have been a very wealthy woman and a great help to the early Church.]
The only way they knew how to make the violet blue color was from the murex snail. Blue violet was an extremely expensive color. The color can be purple, blue or rose, depending on the murex snail.
First, you have to find the snail, which likes to live in about 30 feet of water. In Jesus’ day, they lowered boxes with slates full of clams down into the water and let the box sit on the bottom. The murex snails would crawl along and stick their little front feelers and tickle a clam and the clam would close on it. Then, they pulled the box up and that was how they harvested murex snails.
Then a hole is drilled above the hypobronchial gland to extract the purple dye. It takes 10,000 murex snails to get one thimble full of dye. In 300 B.C. one pound of blue violet dye in 1991 dollars was worth $38,000. One pound of the dye in 300 B.C. was equivalent to two year’s salary. In 300 A.D. there was an edict setting down price control measures because certain things were getting too expensive. One tunic dyed purple, wrung out so you could use as much dye as you wrung out again, cost $100,000.
Ecologically the demand for purple dye was such that the snails were disappearing even though the snails were returned to the sea after the dye was extracted so they could be harvested again.
Fleming, James W. 2002. Desert Spirituality. Biblical Resources Conference Lecture Series, June., pgs 67-70