Rihanna is stepping up as MAC's latest Viva Glam ambassador, and she's bringing her signature shade of red with her. Perhaps inspired in part by the star's cardinal mane of 2011, or her penchant for a good crimson lip, the singer's addition to the MAC Viva Glam family is a bright, blue-based scarlet with a generous amount of sparkle -- and we wouldn't expect anything less. She joins Lady Gaga, Nicki Minaj, Cyndi Lauper, and many more in the elite group of stars who have created a shade for the collection, and just like the previous versions, Rihanna's hue will benefit the MAC AIDS Fund. "The reason this particular lipstick collection is so special to me, is that MAC makes sure that every penny you spend on a Viva Glam lipstick goes directly to the MAC AIDS Fund, which helps men, women, children, and families affected by HIV/AIDS," the star wrote on Instagram. A beautiful duo that gives back to an even more beautiful cause -- we love it! Pick up the gloss for $15 and the lipstick for $16 at maccosmetics.com today. MORE:• Exclusive! Behind-the-Scenes with Rihanna and MAC• Rihanna is the New Face of Balmain• See Rihanna's Many Hairstyles -- On You!