A gem stone plucked from the earth, the sea, or riverbed, often travels across continents to cutting and polishing workshops; and those are increasingly found in India. Far away, the Belgian city of Antwerp is still king in diamond trading. In these two places combined, more than a million people make a living cutting and trading diamonds. Sonja Pace, with additional reporting by Mandy Clark, narrates this segment on the gem trade. (Part 3 of 5)

Gem stones come to Mumbai to be cut and polished

Gem stones come to Mumbai, a busy street in India's commercial hub, to be cut and polished. Nowadays, the majority of the world's diamonds, mostly small stones, are polished in India - in Mumbai, Gujarat, or Jaipur.

The stones are inspected and sorted according to color. They are checked for flaws in the stone, magnified with careful consideration how best to cut. Diamonds are the hardest natural material and only a diamond can cut another diamond. But, it's still precision work - one false move and a stone can shatter.

Sanjay Kambne has been doing it for years. "These are very precious stones," e explained Kambne. "We have to be careful in handling them and working on them."

Working around such precious materials was also a bit daunting for electronics engineer Jayshri Bajaj. Bajaj says she was frightened when she actually held a diamond in her hand - and surprised to see an original.

Bajaj helps maintain the equipment in the workshops. For her, as well as Sanjay Kambne and some one million Indians working in diamonds, it's a good way to support their families.

India's fascination with gems and jewelry goes back centuries

India's fascination with gems and jewelry goes back centuries, explains Sanjay Kothari, head of India's Gem and Jewelry Export Promotion Council. "Since the early years of the 16th, 17th and 18th century, the time of the Maharajas, India has had an affinity for diamonds, jewelry and gold," explains Kothari.

Kothari says gems again became big business in the 1950's and 60's. "Though we do not have any indigenous production of the raw material, all the goods are imported," says Kothari, "and that is how it developed from the 60's to today, and last year the exports were to the tune of $20 billion."

The business is growing at 15 to 20 percent annually.

Halfway across the world, the Belgian city of Antwerp has long been synonymous with diamonds, and to this day it is the world's largest diamond trading center.

Philip Claes is secretary-general of the Antwerp World Diamond Center. "Eighty percent of all rough diamonds are traded in Antwerp, and 50 percent of all polished diamonds are traded in Antwerp," says Claes. "In figures, we have a turnover of over $40 billion each year."

More than 1,800 diamond companies are based in Antwerp. That is definitely why George Read comes to the city. He's a senior vice president with Shoregold, a diamond mining company in Canada.

He carefully sifts through an assortment of rough diamonds laid out on the table in front of him. "The overall parcel here - we're here in Antwerp to have it re-valued," explains Read. "Presently, we're looking at an overall value of $172 a carat. The world average is presently $80 a carat."

Antwerp used to employ 25,000 cutters and polishers, but many jobs are shifting to India

Diamonds are weighed and valued in "carats." Besides carat weight and color, a gem stone's value is determined by clarity and cut -meaning the shape of the polished stone.

Antwerp used to employ some 25,000 cutters and polishers. But, most of those jobs have now shifted to India, where salaries and production costs are lower.

But in workshops in Antwerp or Mumbai, Tel Aviv or New York, it is in the hands of expert cutters that seemingly uninteresting hunks of dark rock are worked over - cut and polished into amazing, sparkling and glistening gems - ready to be set in jewelry and shown off and admired.