Hello there and welcome,
You know just enough
you are asking about authenticity! Excellent.
In a word, YES
That is very thoughtful - your son will love it!
ONLY coal from R.M.S. Titanic Inc., in a little box with certificate, or whatever they sell now, is genuine anthracite recovered from the wreck site. Some samples started their life in Pennsylvania, went across and were placed into Titanic only to head back this way and ultimately sink with the ship because of a recently ended coal strike in Southampton (and before anyone says I am crazy that has been proven http://www.encyclopedia-titanica.org/discus/messages/5932/134337.html?1211222575
). I would stay away from any jewelry (aged recovered coal is very brittle and the jewelry items may have been treated in some way to prevent crumbling) and get a keepsake item or small sample in a box with certificate.
I am looking at the site now - the $25 and $45 items are perfect if they fit your needs.
I will mention I a signed b/w photograph of Eva Hart, Titanic survivor, and a color candid Kodak photo of her at home date-stamped August 1988, way
before the film came out, and thus very desirable. She appears much younger than in later more common photographs from the 1990's. It is not
a strong signature - it is in very light ball point but will appear stronger than in the scan below. There is nothing like it on eBay. Others here will vouch for my items and reputation - ask away. I am NOT interested in putting this on eBay like everyone else, but getting it to the right person. That might be your son. If you are interested, I would sell it to you, for a small
fraction of the insane and absurd $ people are asking now because of the anniversary. I am no vulture.
Eric K. Longo firstname.lastname@example.orgEva Hart, Signed b/w photo, "All good wishes, Eva" in ballpoint, C. 1988Eva Hart color candid, date-stamped Aug 1988http://northatlanticrun.com/735/Tyne_Departure.html