You know you’re in a niche market when your inventory has to survive a 160,000-mph entry through the Earth’s outer atmosphere.

“It’s interesting how you price meteorites,” said James Hyslop, a specialist at Christie’s London who organized a sale of 76 meteorites this past week. Among the factors that affect prices, he noted, are meteorites’ scarcity and the fact that available stock is only occasionally replenished. (A meteor explosion over Siberia in 2013 added significantly to available material.)

Historically, meteorites were valued by gram, Hyslop said. The heavier they were, the more expensive. Recently, however, collectors have begun to take both aesthetic and historic aspects into consideration. “The diamond industry uses the four C’s,” Hyslop said. “We use the four S’s: size, shape, science and story.”

Size is obvious: more meteorite, more money; shape, less so.

“When most meteorites fall to Earth, they tumble chaotically,” Hyslop explained. “You don’t have them plowing straight down.” On the rare occasion that a meteorite does head straight down, its surface heats, then melts, and “you get this wonderful heat shield that has a perfect parabola to it.” Parabola-shaped meteorites, in turn, are much more expensive than others.

The scientific aspect of meteorite valuation is more complicated and is often combined with its story.

“Some of the most sought-after ones are the pallasite slices and spheres that have peridot,” Hyslop said, referring to pieces of a type of meteorite embedded with the greenish gemstone. “Others, like the lunar meteorite, are always incredibly popular.” Hyslop was referring to a piece of the moon that was blown off the satellite by the impact of a very large meteorite, floated through space for possibly millions of years and then collided with the Earth.

One of the offerings at last week’s auction — a 342-pound stony meteorite found in northwest Africa in 2011 — sold for $105,939.