The tidal range is the vertical difference between the high tide and the succeeding low tide. Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth.
Coin toning can intrinsically increase or decrease the value of coins. Natural coin toning can be quite beautiful. It can also be outrageously ugly. And because beauty is often times in the eye of the beholder, placing a value on a coin due to its toning can present problems.
Very valuable coins worth $100s to $1000s of US dollars. Coins in this group range in value from thousands of dollars down to hundreds of dollars. Unless they are heavily worn or have significant damage like scratches, spots, or stains, these coins command high premium values and must be treated with care.