The miner cut its 2018 mining guidance in October from 220,000 tonnes at 3.5 carats per 100t to 200,000t at 3ct/100t.
The Kareevlei throughput number fell below the updated estimate, at 189,990t for the year to December 31, but the final quarter's grade of 4.01ct/100t kicked its production into the black.
Throughput was inconsistent in 2018, peaking at 63,621t in the September quarter, up from 34,247t in the June quarter, when crushing issues caused a 10-day processing halt.
The total production for 2018 was 6,198ct, with 5,805ct sold in the period.
This represented a 71% increase in sales compared to 2017.
BlueRock CEO Adam Waugh said the December quarter's performance was a sign of things to come.
"The results from our second kimberlite pipe, KV1, which came on stream in June last year, and from the undiluted levels of our first kimberlite pipe, KV2, have shown a marked increase in grade, which we expect to continue into 2019," he said.
"Our move to 365-day operations is expected to start in February and is expected to give us around 40% additional plant availability."
BlueRock sold 1,533ct in the December quarter at an average price of US$316/ct, down from the highs of $341/ct in the September quarter and $378/ct in the March quarter.
The miner's share price has been on a steady decline for over two years, with a recent uptick back over 0.3p (US0.38c) still leaving shareholders with a 86% loss from 12 months ago.