Rubysketch - Critical Error: No External ruby installation

[size=200]Help for Rubysketch - Critical Error: No External ruby installation[/size]

This error message may appear when using SketchUp 2013 or earlier on Windows.
If you are experiencing this issue in SketchUp 2014 or greater or on MAC, you should make a new thread.

PlusSpec uses features not normally available before SketchUp 2014, and so where possible it will use an external ruby installation to regain these features.

This error occurs when an external ruby installation cannot be detected.

To fix this issue you need to install ruby using this installer.

To use the installer, simple double click it after downloading and follow the prompts. When given the option to, tick the Enable RubyGems option as shown below

After doing so, restart SketchUp and the problem should be fixed!