RE: Stolkholm quote Gerry, don't get to worked up over the difference in Lucara's SP in different markets day to day, it means nothing. It will always even out in the long run. Some traders use this to their advantage to make a profit, it's called "Arbitrage." Due to the low volume I am not sure how successful this strategy would be with Lucara.
Investopedia explains 'Arbitrage'
"The simultaneous purchase and sale of an asset in order to profit from a difference in the price. It is a trade that profits by exploiting price differences of identical or similar financial instruments, on different markets or in different forms. Arbitrage exists as a result of market inefficiencies; it provides a mechanism to ensure prices do not deviate substantially from fair value for long periods of time. "
Given the advancement in technology it has become extremely difficult to profit from mispricing in the market. Many traders have computerized trading systems set to monitor fluctuations in similar financial instruments. Any inefficient pricing setups are usually acted upon quickly and the opportunity is often eliminated in a matter of seconds.