Thieves have stolen a diamond necklace worth an estimated $1.8 million at an arts fair in the Netherlands police said Friday.

Two women from Mexico and a man from Costa Rica, suspected of involvement, have been arrested, police spokeswoman Renske Hamming said, but the necklace has not been recovered.

Police said the necklace was stolen Thursday afternoon at the fair in the southern Dutch city of Maastricht. The vendor selling it noticed it was missing shortly after having a conversation with the two women, but when she ran after them, the man from Costa Rica "who was apparently together with the women, blocked her," a police statement said.

All three were arrested before leaving the grounds of the TEFAF fair, but the necklace had vanished.

Hamming said police could not comment further on the investigation, but did not rule out further arrests.

The necklace was made in 1948 by American jeweler William Ruser.

Representatives of the art and antiques fair could not immediately be reached for comment.

The fair, which runs through March 16, also features a Van Gogh painting, the 1880 "Child With Orange," valued at $30 million