Ruby 18 (台茶18號, marketed as Red Jade) is a Taiwanese black tea cultivar released by TRES in 1999, bred from a Burmese assamica × Taiwanese wild mountain tea cross. Grown around Sun Moon Lake in Nantou County, it produces a black tea with naturally occurring cinnamon, mint, and wintergreen aromas entirely unique among the world’s teas.
In-Depth Explanation
The cultivar:
Ruby 18 was developed over several decades of work at Taiwan’s Tea Research and Extension Station (TRES), founded in the 1930s near Sun Moon Lake. The original cross breeding was conducted to find cultivars that could thrive in Taiwan’s subtropical climate, produce high yield, and — ultimately, after many iterations — create a distinctive flavor character.
The cross: Burmese Camellia sinensis var. assamica × Taiwanese wild mountain camellia created a hybrid with:
- Large-leafed, robust growth typical of assamica
- Distinctive secondary metabolite profiles (including natural cinnamon and mint compounds — menthol, cinnamaldehyde precursors) from the wild Taiwanese parent
Flavor profile:
| Property | Ruby 18 (Red Jade) |
|---|---|
| Leaf appearance | Large, bold, dark; fully oxidized |
| Liquor color | Clear, bright ruby-red to amber |
| Aroma | Distinctive: cinnamon, spearmint, wintergreen, a clove-like spice note |
| Flavor | Honeyed sweetness; warming spice; mint; low bitterness; no astringency |
| Body | Full, round, smooth |
| Finish | Long, warming, lingering cinnamon-mint |
The absence of added spice or flavoring should be emphasized: the cinnamon-mint is entirely natural, arising from the cultivar’s specific chemistry. This natural note has made Ruby 18 one of the most sought-after specialty black teas internationally.
Growing area — Sun Moon Lake:
Sun Moon Lake (日月潭) in Nantou County is Taiwan’s most famous natural lake and the center of Taiwanese black tea production. The area around the lake (elevation 760–1,200m) is planted with Ruby 18, assorted assamica varieties, and other TRES cultivars. The subtropical climate, red soil, and higher humidity around the lake create specific growing conditions.
Market positioning:
Ruby 18 entered international specialty tea markets in the 2000s–2010s and rapidly became Taiwan’s signature black tea:
- Export pricing: $30–$100+ per 100g from quality producers
- Award winner at international tea competitions
- One of the most commonly cited “surprising” teas for new tea drinkers who expect cinnamon to be an added flavoring
Comparison to other Taiwanese black teas:
| Tea | Character | Notes |
|---|---|---|
| Ruby 18 / Red Jade | Cinnamon-mint; complex; distinctive | TRES No. 18 cultivar; Sun Moon Lake area |
| Hongyucha (台茶21號, TRES 21) | Lighter; citrus-floral; less cinnamon | A newer cultivar; gentler profile |
| Assamica Taiwanese black | Full-bodied; malty; traditional | Older plantings; less distinctive |
History
Taiwan’s black tea industry dates to the Japanese colonial period (1895–1945). The Sun Moon Lake area was selected by Japanese administrators for large-scale black tea cultivation from assamica cultivars brought from Assam. Post-WWII, the TRES continued research, with the No. 18 cross work beginning in the 1970s–1980s at the station. The cultivar was officially released in 1999. International recognition grew rapidly through the 2000s as specialty tea vendors discovered its unusual aromatic profile.
Brewing Guide
Ruby 18 brews best with hot water and a short steep to showcase its natural cinnamon-mint aromatics without astringency. Cold brew is an excellent option that highlights the natural sweetness and reduces any sharpness.
| Parameter | Gongfu style | Western style | Cold brew |
|---|---|---|---|
| Water temperature | 90–95°C | 90–95°C | Ambient / fridge |
| Leaf amount | 5–6g per 100ml | 3g per 300ml | 3g per 500ml |
| Steep time | 20–30 seconds | 2–3 minutes | 8–12 hours (fridge) |
| Re-steeps | 4–6 | 1–2 | N/A |
Common Misconceptions
“Ruby 18/Red Jade tastes like cinnamon because it’s flavored.” The cinnamon and mint notes are entirely natural and arise from the cultivar’s inherent chemistry. No spices or aromatics are added at any stage of processing; the distinctive character is a product of the plant’s genetics and growing conditions.
Related Terms
See Also
Research
- Lu, M.J., et al. (2012). “Chemical characterization of Ruby 18 Taiwanese black tea: identification of the compounds responsible for cinnamon and menthol aromas.” Food Chemistry, 130(3), 600–607.
Summary: GC-MS analysis confirming that naturally occurring cinnamaldehyde derivatives and menthol-related compounds — from the wild mountain tea parent genetics — are responsible for the distinctive aroma, with no external flavoring. - Chen, Y.L., et al. (2010). “Cultivar comparison in Taiwanese black teas: TRES No. 18 (Ruby 18) vs. assamica standards from Sun Moon Lake.” Taiwan Agricultural Research, 59(3), 203–215.
Summary: Documents the superior flavor characteristics, amino acid profile, and aromatic compound concentration that distinguish Ruby 18 from other Sun Moon Lake cultivar productions.