High frequency for gold and lower frequency for coins...I know over the years all gold nugget machines were real high frequency units but most are interested in gold rings and they are mixed with other metals which may or may not make higher fequencies better for gold jewelry...Any input appreciated...One club member had a unit where he could change from one freq.to the other and always used the low frequency so one wonders as he got as many gold rings as fellow clubmembers. Just a thought for discussion as the paint is not dry on units and they are talking about high frequncy coils...I really don't know but has anyone experimented and could add their thoughts..