The curious case of an enormous emerald weighing about as much as a horse is being heard in a Los Angeles courtroom where a judge will try to determine precisely who owns it.

Dug up in Brazil in 2001 and tipping the scales at 381 kilograms, the boulder-sized Bahia Emerald is one of the largest gems ever discovered.

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This photo provided by the Los Angeles County Sheriff's Department shows the so-called Bahia Emerald. Dug up in Brazil in 2001, the boulder-sized Bahia Emerald is one of the largest gems ever discovered. ((Los Angeles County Sheriff's Department/Associated Press))

Several people have laid claim to the hulking rock throughout the years. Now a small army of lawyers is crammed into a tiny downtown courtroom, where Superior Court Judge John A. Kronstadt will review the case of the man who says he bought it first.

Tony Thomas has said he purchased the emerald from a Brazilian gem dealer for $60,000 shortly after it was excavated. Its worth has since been appraised at almost $400 million.

But after he arranged to have it shipped home, Thomas says he was tricked into believing the emerald was stolen so it could be sold to someone else for more money.

He says it vanished after he turned it over to people who were supposed to ship it to him and, now that it's been found, it should be returned to him.

The case will be weighed from the bench by Kronstadt without a jury, and he will listen to oral arguments about Thomas's claim.

Lawyers for other interested parties have argued the claim should be dismissed because the emerald was never delivered to Thomas, but his lawyer says Thomas did take possession of the emerald in Brazil before it disappeared.

The judge will review other claims later.

The rock's strange journey

After it vanished, the rock and its history took confusing turns. At one point, it wound up in a warehouse in New Orleans which was flooded during Hurricane Katrina.

Among those claiming ownership is a man who says he was retained by the Brazilian owners to sell it.

Another claimant has said he received it from a gem dealer as collateral for a shipment of diamonds he paid for but never received. He was trying to sell the gem in Las Vegas when authorities seized it.

The Los Angeles County Sheriff's Department now has the emerald under lock and key.