BEDFORDVIEW, SOUTH AFRICA - Mosibudi Jo Mathole and Khomotso Ramodipa are rare gems in the male-dominated diamond industry. The South African sisters run one of the few women-owned diamond polishing businesses in the world. And, despite the slumping global market for diamonds, and a shrinking industry in South Africa, they've managed to keep shining and developing new female talent.

A passion for diamonds drove South African sisters Mathole and Ramodipa to drop their careers as an investment banker and an optometrist.

After qualifying as diamond valuators, in 2008 they started a cutting and polishing shop, Kwame Diamonds - the first and only one run by sisters in South Africa.

Many barriers to entry

Entering this industry is not easy explains the company's founder and director, Mosibudi Jo Mathole.

"The barriers to entry go beyond just being a woman or being a man, because the difficulty boils down to having an outfit like this, you really need a proper capital outlay. And for women it becomes a bit tricky because this has always been a very male-dominated industry."

But seeing challenges as opportunities, the sisters cut their way into the diamond industry, selling only responsibly sourced, certified stones bought from mining companies operating in South Africa.

Kwame Diamonds carved out a niche in cutting and polishing fancy and bespoke cut diamonds.

Among the best

They are also accredited to cut and polish world-renown De Beers Group's branded diamonds, says co-owner and director, Khomotso Ramodipa.

"To be able to produce a Forevermark diamond, which according to them, it's 1 percent of the world diamonds that are produced. ... If you are able to polish that kind of diamond, then you are among one of the best," she said.

Mathole and Ramodipa employ and empower women in the diamond industry by developing their skills. Diamond polisher Grace Tshego's repertoire now includes more than the round cut.

"Now I can go out there and say, 'I'm a diamond cutter. I'm even specializing with fancy cut.' It's something that is so wow, cause other people they don't know it."

Shrinking diamond business

Globally, polished diamonds' profit margins are declining.

The South African industry shrank from 4,500 polishers 25 years ago to 250 polishers today.

But the sister-run Kwame Diamonds has managed to not only stay in the market but gain a reputation for innovation, according to the president of the World Federation of Diamond Bourses, Ernie Blom.

"They're looking at the diamond industry from a different perspective," he said. "They're thinking out of the box. And maybe they're ticking all the right boxes that is giving them the success that they have. And maybe that's what a lot of the older diamond industry can learn from."

Many in South Africa's diamond industry fear a lack of growth will cause a shortage of jobs for trained diamond talent, but not Mathole.

"How you approach the business is what will set you apart," she said. "So yes, it is shrinking, but we are here not to shrink. We are here to make sure that we expand."

These dynamic sisters are determined to prove not just that diamonds are a girl's best friend, but that the industry is a place where women can shine.