The problem is as following.
Error installing libv8: ERROR: Failed to build gem native extension. D:/Ruby193/bin/ruby.exe extconf.rb creating Makefi
do: gem install rmagick -v '2.13.2'
gem install rmagick -v '2.13.2'
and then do: gem install libv8 -v 3.11.8.17 -- --with-system-v8
gem install libv8 -v 3.11.8.17 -- --with-system-v8