brew install ImageMagick
gem install rmagick
uilding native extensions.  This could take a while...
ERROR:  Error installing rmagick:
  ERROR: Failed to build gem native extension.

        /Users/lifejimmy/.rvm/rubies/ruby-1.9.3-p374/bin/ruby extconf.rb
checking for Ruby version >= 1.8.5... yes
extconf.rb:128: Use RbConfig instead of obsolete and deprecated Config.
checking for /usr/local/bin/gcc-4.2... yes
checking for Magick-config... yes
checking for ImageMagick version >= 6.4.9... yes
checking for HDRI disabled version of ImageMagick... yes
checking for stdint.h... yes
checking for sys/types.h... yes
checking for wand/MagickWand.h... yes
checking for InitializeMagick() in -lMagickCore... no
checking for InitializeMagick() in -lMagick... no
checking for InitializeMagick() in -lMagick++... no
Can't install RMagick 2.13.1. Can't find the ImageMagick library or one of the dependent libraries. Check the mkmf.log file for more detailed information.

*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
  --with-opt-dir
  --with-opt-include
  --without-opt-include=${opt-dir}/include
  --with-opt-lib
  --without-opt-lib=${opt-dir}/lib
  --with-make-prog
  --without-make-prog
  --srcdir=.
  --curdir
  --ruby=/Users/lifejimmy/.rvm/rubies/ruby-1.9.3-p374/bin/ruby
  --with-MagickCorelib
  --without-MagickCorelib
  --with-Magicklib
  --without-Magicklib
  --with-Magick++lib
  --without-Magick++lib


Gem files will remain installed in /Users/lifejimmy/.rvm/gems/ruby-1.9.3-p374/gems/rmagick-2.13.1 for inspection.
Results logged to /Users/lifejimmy/.rvm/gems/ruby-1.9.3-p374/gems/rmagick-2.13.1/ext/RMagick/gem_make.out

$ cd /usr/local/Cellar/imagemagick/6.8.0-10/lib
$ ln -s libMagick++-Q16.7.dylib   libMagick++.dylib
$ ln -s libMagickCore-Q16.7.dylib libMagickCore.dylib
$ ln -s libMagickWand-Q16.7.dylib libMagickWand.dylib