Maker: Sheaffer. You may be looking for a different model of Admiral, depending on vintage; there is a Balance, the Touchdown in fat and Thin Model, or the Snorkel version to consider. This page refers to the Triumph era version.
The only real difference between the Crest and the Sentinel is that the former has a gold-filled brass cap rather than one made of stainless steel. There were pens above the Crest in the roster, but one begins to look at all-metal bodies and solid gold components.
Production Run: 1942 – 1948.
Cost When New: $17.50 (for modern value, try this calculator).
Size: 13.1 cm long capped, 14.8 cm posted, 11.2 cm uncapped.
Point: 14k gold triumph with platinum mask.
Body: Celluloid until 1947, then Forticel.
Filler: Vacuum, capacity approx. 1.2 ml or lever, capacity approx. 0.9 ml.
Sheaffer Crest, vacuum filler. This is likely a 1947 or 1948 model, being a solid colour that isn’t black.
Before the spring of 1948, Sheaffer put the white dot on metal-capped vacuum pens on the tail, as they hadn’t hit on the secret of reliably attaching it to the cap; it would not do to have the very mark of superior quality dropping off the pens.
If you are relying on the preceding information to win a bet or impress a teacher, you should read the site’s scholarly caveat. Remember, this is the internet, and it’s full of bad information.