You can use the chardet gem to detect the charset of an arbitrary string.
Install the chardet gem by issuing the following command:
```ruby
$ sudo gem install chardet
```
Then in irb:
```ruby
require 'rubygems'
require 'UniversalDetector'
p UniversalDetector::chardet('Ascii text')
p UniversalDetector::chardet('åäö')
```
The output from this example is:
```ruby
{"encoding"=>"ascii", "confidence"=>1.0}
{"encoding"=>"utf-8", "confidence"=>0.87625}
```
For Python users there exists an identical library...