Counterfeit sovereign / half sovereign - How often are they gold?

I know sovereigns have been counterfeited as long as the denomination has been around. Some are full weight and are not meant to deceive collectors or cheat anyone but rather to resemble familiar currency when they're otherwise unavailable. But for those that are made to cheat people and trade at face value, are they mostly gold plated or are they underweight gold? There must be a lot of cumulative experience here from which we can get close to an answer. Thanks
"For every complex problem there is an answer that is clear, simple, and wrong." H.L. Mencken
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If they are not up to snuff in fineness and weight then they were created to part of a bonafide fraud attempt - and were likely made beginning in the late 1960s early 1970s when things really started coming unraveled in Lebanon and Syria.
The link below is a good article on counterfeits, but it doesn't answer all of my questions.
http://www.ngccoin.com/news/viewarticle.aspx?IDArticle=3382&Counterfeit-Sovereigns
This really does not answer your question, but I hope that it inspires others to comment.
<< <i>Some are full weight and are not meant to deceive collectors or cheat anyone but rather to resemble familiar currency when they're otherwise unavailable. But for those that are made to cheat people and trade at face value, are they mostly gold plated or are they underweight gold? >>
Slightly debased gold seems to be most common. Sovereigns are supposed to be 22k gold. Many of the Middle Eastern counterfeits I have seen - they could perhaps be called "replicas", since they're really intended as private bullion rounds rather than as outright frauds - are the correct weight but made of 21k gold - at least, that's what the jeweller has stamped on them. If they sell even just a few of them to unsuspecting customers as 22k coins, there's enough profit to justify their manufacture. Example posted on CCF.
Gold is almost unique in its high density. Most other metals of similar density are either scarcer and more valuable than gold (like platinum) or are fiendishly difficult to work with (like tungsten). This makes making a fake gold coin out of fake gold that is both the correct weight and the correct thickness virtually impossible; either the weight will be right (and the fake look twice as thick as the genuine) or the thickness will be right (and the weight only half that of the genuine).
Roman emperor Marcus Aurelius, "Meditations"
Apparently I have been awarded the DPOTD twice.