Rihanna in Zac Posen at the First Annual Diamond Ball

It’s not like Ri has to attend every party in some outrageous outfit with her nipples out, but this just doesn’t feel like her: Rihanna hosted the First Annual Diamond Ball to benefit The Clara Lionel Foundation in Beverly Hills, California in a Zac Posen gown accessorized with Chopard and Repossi jewelry. Zac Posen Fall …