By CHERYL BELZNER
Of The Daily News

John Cryderman's palms were sweaty and his heart pounding when the call came.

"At first I thought it was a crank call," recalls Crydennan with a laugh. "But it was real."

It was from the British High Commission in Ottawa, giving him the go-ahead to build a boomerang for Prince Charles.

His Royal Highness, who rarely accepts gifts from the public, gave Crydennan the royal nod to craft the item.

Now Crydennan spends his nights and weekends in a basement wood shop, carving, sanding and polishing his dreams into reality.

"I always wanted to donate something (to the royal family) but I never knew what.

"It's crazy really."

Cryderman, who's been collecting and crafting 'boomerangs since 1987, wrote to the commission in September outlining his detailed plans. He didn't expect a response.

But when Rosemary Doyle-Morier, the commission's chief of correspondence and requests, called, he was elated.

THE PRINCE RARELY accepts gifts from the public, she says from Ottawa. "Only when he has a strong personal interest and if the person has put a great deal of thought" into the gift.

Crydennan has been concocting plans for the last two years. He put ideas to paper this year.

The two boomerangs, crafted from a variety of exotic woods, will feature a polo-playing prince carved into the wings. His polo stick and horse's hooves will be outlined in solid gold, the reigns in silver, Sheaves of wheat, representing Canada and the royal family's concern for world famine, will sparkle with gold.

Royal crowns on each boomerang will be embellished with cow bone, mother of pearl, gold and the hard white insides of a coconut-like fruit called an ivory palm.

They'll be propped up inside a walnut case with padded cow hide cushions. Resting beside will be royal wax and cloth (adorned with a polished green stone in a boomerang shape) to shine the treasures.

The case will be highlighted with Indonesian rosewood, bronze and silver. Crydennan estimates the cost at $9,000, not including his 400 hours of labor.

BUT THE HONOR of having his work displayed in the royal castle far exceeds his expens-es, he says.

"Very few people do what they want to do," he says. "Not many people get the honor of having something accepted by the royal family."

He hopes to present his gift to the prince in the spring, on behalf of himself, Chatham and Canada. Forsyth Travel and Canadian Airlines will give him a return ticket to England.

Crydennan says it's been a humbling experience.

He's already been coached on royal etiquette and chuckles at his last letter to the prince. It was a question which had to be answered.

"The sport and art of throwing the boomerang can only be mastered if the boomerangs conform to the thrower's handedness," writes Crydennan.

"Embarrassing as it is for me to ask, is His Royal Highness left or right handed?"

It makes a difference when crafting the boomerang, he says.