Some true diamonds are coloured from inclusions or structural differences. Can the prices of these diamonds be predicted with the models we make for traditional clear diamonds?
One website lists a black diamond that weighs 1.44 carats for \(\$ 3050\). Black diamonds are true diamonds but may have formed from impacts of comets, asteroids, or meteors rather than from geological pressures deep underground. They're probably best compared to the most-coloured K-quality diamonds. Here's a scatterplot of Price vs. Carat Weight for K-colour diamonds. The black diamond (shown with a red \(\mathrm{x}\) ) has both high leverage and large residual.

The same site lists a blue diamond that weighs 0.82 carats for \(\$ 16,500\). Blue diamonds are a luxury item, best compared to the best D-colour clear diamonds. Here's a scatterplot of Price vs. Carat Weight for C-colour diamonds with the blue diamond shown as a red \(x\).

QUESTION

What would be the effect of including these exotic diamonds on regression lines fit to each of these scatterplots?

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Price 8000 6000 4000 2000 1.0 1.5 2.0 2.5 Carat Weight