Greetings Karen,
A friend once sent me an entire discussion regarding Tyrian purple; there were arguments on its actual shade with much referencing. I will try to dig through my old emails to find that.
In the meantime, here are a few links:
http://en.wikipedia.org/wiki/Tyrian_purple (caution advised)
http://www.chriscooksey.demon.co.uk/tyrian/index.html
http://www.perseus.tufts.edu/cgi-bin/pt ... +Nat.+9.60 (I believe this is Pliny's work)
On the other hand:
http://community.middlebury.edu/~harris ... urple.html
and from Aramco World, another idea:
"One of the trade secrets of the Tyrians probably was the mingling of the dyes from the two different shellfish; for the Murex, if used alone, produced a dull, dark purple and the Buccinum, a red tone which faded easily. Buccinum red was less in demand—200 pounds of Buccinum dye brought only 111 pounds of the Murex. It was by immersing a cloth, first in the dye of the Murex and then in that of the Buccinum, that the dark, rich color known as Tyrian purple was obtained. It has been described as "the color of coagulated blood, but when held up to the light showing a crimson hue."
And now, I will see if I can find that longer article. I believe there were several ancient sources quoted from both sides, so it might be of help. If I recall, the discussion was from a group of weavers who only use natural dyes, and who were somewhat adamant about accuracy in reproducing "old" colours (smiling)
Regards,
Sikander