Ask McArdle: Where does one find a diamond as big as an egg?

Also: betting on your kids

(Peter Arkle)

(Peter Arkle)

Can I bet on my kid making it to the big leagues?

Last weekend Wee McArdle and I were out for a stroll when we came upon an abandoned melon. On a lark, the young lad booted the honeydew with his full might. It flew 35 yards, easily passing between two upright branches on a distant tree. The feat confirmed my suspicions—my boy will be a placekicker in the mighty CFL. And should I wish to place my money where my mustache is, bookmakers will take the wager.

Thirteen years ago, Peter Edwards walked into a Welsh betting shop and inquired about making a £50 bet that his two-year-old grandson would one day play for the national team. After a phone call back to head office in London, the bookmakers offered him 2,500-to-1 odds. So when 16-year-old Harry Wilson stepped on the field on Oct. 15, his grandfather collected £125,000 and retired a year early from his job as an electrical contractor.

Such long-term bets have become so common in the U.K. that most betting shops have standard rates for gambling on a child’s future. Before the age of six, Ladbrokes offers 1,000-to-1 odds on a child playing for the English national team and 500-to-1 on the child making it to the Premier League in soccer. Earlier this year, Ladbrokes began taking wagers on students receiving their university degrees with certain levels of distinction. The bookies consider the student’s previous marks against the difficulty of the degree to generate the odds. So if you can’t bet on a football career, you can always bet on Oxford instead.

Where does one find a diamond as big as an egg?

I always check between the couch cushions at my friend the Emir’s place.  My prospecting has yet to yield a giant diamond, but it does produce the occasional gold coin and a lot of stale Cheetos.

But you’re probably wondering about the 118-carat oval diamond recently sold at auction for $27.3-million. The stone was discovered in southern Africa in 2011. Beyond that, however, the exact location of the mine, the original owner and the name of its purchaser are cloaked in mystery. What I can tell you is the diamond originally weighed 299 carats, comparable to a Mr. Big bar. But it lost 60% of its mass when it was cut to size, leaving it with the heft of roughly four loonies.

Whoever purchased the rare gem also garnered the right to name it. While diamond monikers generally evoke exotic refinement—the Mouawad Splendor, the Star of the South—I prefer the description used by a Sotheby’s spokesman in the New York Daily News. Calling it “the Honker” could only hike its value.

How fast should revolving doors spin?

North American safety guidelines dictate a revolving door can spin a maximum of 12 times per minute, with most regulating their speed via a complex gearbox. Originally known as a “storm-door structure,” the revolving door was first patented by Theophilus Van Kannel of Philadelphia in 1888 (his other inventions included a device for removing cherry stones and the Witching Waves, an amusement park ride with a rather high injury rate).

His company changed its name over the years, but it continues to produce whirling doors as the International Revolving Door Co. Moreover, the IRDC contends that an optimal door can handle 2,400 entrants and exiters per hour. Operating at maximum speed, that should allow two-thirds of a person in-and-out each second. That does not count for regional differences. “Pedestrian traffic in the North and East is generally faster than it is in the West and South,” advises the IRDC. You’ve been warned—you can lollygag in San Francisco, but best be fleet footed in Boston.

Need advice? Want to settle a debate? Go ahead, ask McArdle anything: