What are fracture filled diamonds, and how recognise them?

I recently met with a jewellery valuer who values all types of jewellery. One of the services this valuation company provides is insurance valuations for diamond engagement rings that were purchased abroad, mainly Antwerp, Dubai and New York. Several Irish couples head to these locations each year in the search for a better deal, as they believe Irish Jewellers are too expensive due to higher margins, overheads etc.…