the perfect explanation to why there are diamonds on measuring tapes

The black diamond marker on a tape measure falls between the 16-inch and 24-inch spacing. This marker is commonly used in building a concrete block chimney. But, it has other uses too.

Marked at 19.2 inches apart, using this type of placement also allows for more weight loads with fewer pieces of wood. New Wood Worker notes that while this can save money, it may not meet building codes in all areas.
If you aren’t planning on building a house, you can still use these numbers to build a sturdy shed or find studs in the wall of your home. (If the 16-inch measurement isn’t working, try the black diamond next.).