While marquise-cut diamonds aren't nearly as popular as the round-cut, oval-cut, or cushion-cut, they are a unique and sought-after diamond shape. 

It really depends on the quality of the marquise-cut diamond. A diamond's carat weight isn't the sole indicator of its cost.  A natural 1-carat marquise-cut diamond can cost anywhere from $2,000 to $10,000. Lab-grown diamonds cost even less, from $600 to $2,000 for a 1-carat marquise-cut stone. 

No, marquise-cut diamonds aren't more expensive. The most expensive diamond shape is the round-cut. If you are looking to save on your diamond, choose a lab-grown diamond instead, which can cost 30%-50% less than an earth-grown stone.

Yes, a marquise diamond can be recut into a new shape, but by doing so you will be sacrificing the stone's carat weight. You'll need to find a diamond cutter who can recut the stone for you. 

It really depends on many factors, such as the diamond's cut, color, and clarity grades. A 2-carat marquise-cut diamond can cost anywhere from $10,000 to $40,000 or more. A 2-carat lab-grown marquise-cut diamond will cost even less, from $4,000 to $7,000 or more.

This shape was the most popular in the 1970s, although it dates all the way back to the 18th century.