After studying two caves in Spain (near Sevilla and Barcelona), scientists discovered several beads that looked like amber. Archaeologists were puzzled since these beads were among items made of real amber. In fact, these items were mollusks and seeds covered with resin. The discovery was made in an artificial cave where, according to researchers, 19 people were buried. They believe that amber was a valuable commodity at that time, and trading amber was a popular business. It was used for amber jewelry as well as for medicinal purposes. Until now, we knew that people were using amber for thousands of years, but this is the first evidence of amber counterfeiting.
A full study published here: https://doi.org/10.1371/journal.pone.0215469