@JBarry:
You are correct for Riddles 1, 2, and 4. Sadly, the answer to Riddle 3 is not ebony. Still, a good attempt. And thank you for the numbering; I suspected what you were associating each one with, but I wanted to make certain.

A perfect amount of reasoning, covering everything I was thinking of when formulating the riddle.

Again, excellent reasoning. A few additional bits of trivia: The actual coral polyp (yes, that's what they're called) looks like a miniature sea anemone, and thus, quite flowerlike. And not just treacherous and sharp, but huge also...Australia's Great Barrier Reef was what I had in mind when I wrote that line. Hard to believe something so small can create something so big, huh?

Not just 'were harvested'. According to encyclopedia.com, Japan still (at the time the entry was written, at least) has the lead in cultivating saltwater pearls, while China bears the same for freshwater pearls. And I'm not sure 'everyone' has heard of Mother of Pearl, but yeah, most people have. Another excellent bit of reasoning.

Again, though, the answer to Riddle 3 is not ebony. There's another substance I have in mind, although it's not as well known as the others. Think about what common factors the other three have, and then go looking for something else that fits that description.

kinda a stretch......... but i might be persuaded to think that the third riddle actually refers to coal or other fossil fuels...........originally they where plants that required light to grown, but now they are black as night.........wood for example could be in fossil fuels that grew where the ocean was in prehistoric times and now is in some of the oil we mine in our offshore wells

that would mean that the overall would have something to do with Ancient life, things that where once something else or are no longer.

Extremely close, but not quite there. Dig a bit deeper using your current line of reasoning.

lol hmmmmmm.....................

am i rethinkin both of the answers or?

Both, but not by much.

I'm gonna take another short stab at this, and say that number three might be Jet.
Some sources compare it to black amber, and others stipulate that its formation comes from wood under high pressure and salt water, which fossilizes it. Even more sources say it is lignite in one of its forms(soft jet), which is coal; and, that imitations of jet have been made from anthracite.
All of this is, like the rest, something known in antiquity and used for ornaments and jewelry. Beads and necklaces, with a heavy cotton thread to hold the beads in place.

Am I close, EnderX?

i thaught jet earlier but i didnt think ut was right

You are correct for number three, JBarry. The first description I found for Jet some time back called it 'gem-grade coal', which kind of caught my attention.

And now, knowing that the answers are Amber, Coral, Jet, and Pearl, the answer to the final riddle should become apparent. Anybody willing to take a shot at it?

ivory?

all things that either are usless or non-valuable until processed.......pearls are just dirt in the beginning, jet has to be made into jewlery, a piece of coral is lame until it is in a coral reef, and amber unless it has an ancient extinct bug or something in it is just a hunk of dried sap..........

doubt it's right lol