Cumaru is often sold as "teak", which it isn't. Real teak also comes in different grades. The best teak (honey-brown is color with close grain) can be difficult to come by, as it is all snapped up by the furniture manufacturers. It's also expensive (one can often buy the furniture for less than you could buy the wood to make it). Pale brown teak is dull-looking, but cheaper. I'm still working through a box of 1"x1"x8" teak blanks that I bought for around $0.50 each (which comes to $9.00/bdft). Most teak (not burl) I see nowadays sells for $12.00 to over $50.00 per board foot.
As has been said, regular teak doesn't show much in a pen. Teak needs a larger piece to display its beauty. Teak burl, on the other hand, is gorgeous.
Teak generally has a high silica content. Although it is relatively easy to work, it dulls tools quickly.
Regards,
Eric