The $5 million price tag attached to the moon rock stolen from the Mdina museum was "realistic", according to two experts.
As police continued their search, it was also learned yesterday that the thieves who broke into the National Museum of Natural History on May 18 took the moon rock plaque to the second floor before they dismounted it and made their way out of the museum.
Joseph Gutheinz, a retired Nasa Office Inspector, who was instrumental in retrieving a stolen moon rock in Honduras, has in the meantime offered to assist the Maltese police.
Speaking to The Sunday Times last week, Mr Gutheinz urged the Maltese authorities to implement a 48-hour amnesty period to help retrieve the precious rock.
The rock - a 3.9 bn-year-old lunar sample no bigger than a couple of centimetres - was picked up by Apollo 17 astronauts Eugene Cernan and Harrison Schmitt from the moon's Taurus Littrow Valley during their mission in December, 1972.
A total of 380kg of moon rocks was collected by Apollos missions 11, 12, 14, 15, 16 and 17 and around 100kg were donated to those countries deemed friends of the US.
Alex Gatt, founder of the Institute for Astronomy and Astrophysics, said there were several suggestions which indicated that the rock was worth some $5 million (around Lm1.7 million).
It was enough to look at the market value of previous stolen pieces to realise how much they were worth.
A 600-pound safe full of moon rocks and meteorites was stolen from the Johnson Space Centre in Houston in July, 2002. Subsequently, former space centre employees and another man were charged with trying to sell stolen moon rocks from the Apollo missions for between $1,000 and $8,000 a gramme.
The moon rock stolen from Mdina had incidentally been loaned to Dr Gatt for a few days to be displayed in an astronomy exhibition at Villa Bighi, Kalkara, a few days before it was stolen.
For astronomy enthusiasts, the disappearance of the moon rock is a tremendous loss, Dr Gatt pointed out. In fact, he said that the Maltese authorities should try to obtain a replacement from the US if it is not retrieved.
Dr Gatt claimed there were markings on the wooden base close to the Lucite ball signifying that a previous attempt at its removal had been made.
Museum officer John Borg would not put a price to the rock but pointed out that its value was "astronomical".
"Sadly, we still tend to rate precious science pieces as second rate artefacts in comparison to archaeology pieces. I consider them as important as the statue of the Sleeping Lady."
He said the police and the museum authorities were leaving no stone unturned and were investigating all the people who had entered the museum on the day of the theft, including several primary school students and tourists.
However, Mr Borg added: "Whoever took it had been here once before. I believe the theft was planned."