test3.rb

#!/usr/bin/env ruby
#encoding: utf-8
require 'win32/registry'

begin
    Win32::Registry::HKEY_CURRENT_USER.open("Software", Win32::Registry::KEY_ALL_ACCESS) do |reg|
        reg['test2'] = 'åáâäãā'
        reg['test3åáâäãā'] = 'åáâäãā'
        value = reg['test']
        puts value.encoding
        puts value
        puts value.inspect
        reg.each do |v|
            puts v
        end
    end
rescue Win32::Registry::Error => e
    puts e.message
end