My Gear

Hello. I was wondering if someone could look over my gear and see if I have the correct gems. I'm kind of new to WoW and so it's still a learning process. :) I've also noticed I've not been able to obtain 25k+ DPS according to recount after an entire HOT encounter. Would you think it's related to my gear, gems or perhaps my rotation.

Thanks.
.07 under hit. As an Unholy DK, you do not need expertise. So reforge out of any exp you have.

Unless you have Gurthalak, reforge into haste after the 8% hit cap.
You'd want to prioritize reforging into Haste regardless of whether or not you have Gurthalak. Since you aren't using Gurthalak, Haste > Crit > Mastery. You want to get your Hit to 8% and get rid of all of that Expertise.

Get rid of Glyph of Icy Touch and replace it with Glyph of Death Coil. Death Coil is generally always in the top 3 on my Recount's list of my damaging attacks, and +15% DC damage is WAY better than the bonus to Frost Fever. I'd also suggest using the Anti-Magic Shell glyph, as that adds 2 seconds to your RP-soak. Get rid of all of your Minor Glyphs except the Blood Tap glyph, and replace them with Death's Embrace and Horn of Winter (unless you need Resilient Grip for some reason). Personally, I talent into Improved Blood Tap instead of Contagion. I find that having Blood Tap on a 30 second cool down is a bigger improvement to my DPS than the bonus to the damage of diseases spread via Pestilence.

Then again, maybe gear isn't your issue. Perhaps you're not utilizing Reaping as much as you should?