Haddrell's of Cambridge New ZealandManuka Honey. Manuka trees are indigenous to NZ and honey made from the Manuka blossom is a very delicious, earthy honey that has unique properties. These properties can be measured in a laboratory by testing for key compounds. The world’s most trusted and rigorous method of grading Manuka honey is to measure the ‘Unique Manuka Factor’ (UMF). Honey that achieves a UMF rating has been proven to contain the three signature compounds found in genuine Manuka Honey (Leptosperin, DHA, and Methylglyoxal (MGO)), and buying honey with the UMF rating is the best way to ensure you’re buying genuine Manuka Honey with a measurable purity.