When hair comes in to G & G Hair Extension, it all looks just about the same -- long, straight, black. Pretty much like what it is -- hair from the heads of women in countries like India and China.

But with some twisting and curling and combing and dyeing, by the time the hair leaves the store, it can look like the perfect fit for a lot of women's heads -- Hispanic, Black, White.

Behind this process, however, are several global factors that have caused many changes to the business in recent years.

Hair extensions and weaves, for decades have been a part of the hair-care repertoire of black women, have become increasingly popular among other ethnic groups, along with a growing roster of celebrity clientele.

And the supply itself is changing, as women who used to have long, unprocessed hair perfect for extensions have started to change their styles.

The countries of Asia, particularly India and China, have for years and years been a goldmine for hair. Cultural aesthetics have encouraged women to grow their hair long, and dyeing and other chemical processes popular in the West and potentially damaging to hair have only recently been making inroads.

Women have also been willing to give their hair up, either for profit or principle, whether by offering the hairs that get caught in their brushes, or by cutting off years of growth at a time. In India, for example, a religious practice calls for the cutting of hair as a sacrifice, and at least one large temple in India has brought in much money for the institutions by selling the hair the devotees shave off.

Aside from the length, Chinese and Indian hair also have another advantage -- the strands are strong enough to handle the color stripping and other steps it takes to turn Asian hair into something that matches other women.

"The Chinese hair handles the process the best," with the Indian hair close to it, said Gary Teitelbaum, owner of Adorable Hair-Do Corp., in Manhattan. While most hair for extensions is processed outside of the country and brought into the United States already packaged, there are some places like Adorable and G&G that do it themselves.

And what a process it is. The hanks of hair are separated into sections, and wrapped tightly into coils around wooden sticks of various thicknesses. The sticks go through a procedure of boiling and drying that makes the hair curl. To change the color, the pigment is chemically removed and the new color added in.

The result is a product that's remarkably varied in appearance. Straight, wavy, curly, in a range of colors from red to blond to black.

"I can get any texture I want now," said Diane Da Costa, a stylist and author who specializes in working with textured hair and extensions.

"You can have the European straight look, you can have the African kinky look," said Thembi Mhlambiso, 26, of Nyack, New York, who has been wearing extensions for years. "Weaves are great for me."

Her main concern with extensions is making sure they blend inconspicuously with her own hair, not what they used to look like.

"I've never thought it about from the angle of I'm wearing someone else's hair," she said.

Those who are in the business of human hair extensions, though, are clearly aware that they need someone else's hair -- many people's in fact -- in order to make their business run. And at a time when the popularity of extensions is exploding, other global factors are making getting the hair more challenging that it used to be.

Realizing they have a lucrative product, the hair dealers who amass the hair from women's heads are charging more for it, Teitelbaum said.

"The communists are now capitalists ... they want their price," he said.

And demand has grown in the European market, where hair sellers can get good prices for top-quality hair, said Enrique Gamez, the manager at G&G.

"There have already been times when I needed 20-inch hair and it's been hard to get and the price will go up," he said.

And in countries like India and China, improving economies mean other possibilities for employment and income. That means women don't have to use their hair as a money source, said Sheila Stotts, a hair care specialist for celebrities who buys the raw hair to process for her clients' extensions.