At this time, Annie Sloan Chalk Paint does not offer a dark purple (or bright pink), pre-mixed, so knowing how to mix your own is the only way to add it to your color palette.
I used the same process that was used for the red-yellow color options, a 1/2 cup measurement for equal parts. The middle column shows what happens when Pure White is added to each result. These are similar to the purples that are available pre-mixed from Chalk Paint.
If you are trying to match exactly any of the Chalk Paint colors, you may be disappointed. Annie Sloan's formulas for paint colors are more complex than merely mixing 2 of them. But, if you want to add a range of purples to your palette, this is an easy and inexpensive way to do it.
Here are some ideas found on Pinerest to use custom mixed purples.
Mixing standard colors in different amounts and combinations is a great way to create a diverse and unique color palette. To see some the custom colors you can make from Annie Sloan Chalk Paint®, see my posts, Mixing for Green, and Mixing for Orange.
I like Annie Sloan Chalk Paint for my craft and furniture projects, but for walls nothing compares to Pure & Original Fresco Lime Paint. I love the natural variations of shades and tones the lime creates within one paint color. You have to see how gorgeous it is! Checkout my most recent interior design make overs with Fresco. It can be purchased online at www.502paint.com
P.S Pure and Original also makes a chalk based paint called Classico in 140 colors! Its amazing too!