Bulgarian customs officials busted a diamond smuggling attempt at the Sofia Airport last week, news outlets report.

According to the Standart website, authorities found one of the suspects in possession of a mail order catalog in which were concealed four diamonds with a combined weight of 2.1 carats. The stones’ value was estimated at $3,400.

The Standart quoted experts who observed that smugglers were following market trends and switching from drugs to diamonds.