YiDeGe liquid ink, started in 1865,  is absolutely top one Chinese liquid ink band.In Chinese market. 80% liquid ink is YiDeGe; however, over 60% of them are fake. Fake ratio are even more higher in US. 

We promise our  YiDeGe ink are original authentic, and purchased from Beijing Yidege Ink Industrial Co., Ltd. directly. And all our inventory purchasing/selling history and volume on eBay are reported to and under the monitor of  Beijing Yidege Ink Industrial Co., Ltd.. Currently our YiDeGe products are selling at almost no profit to meet U.S. demands. 

Never pour used ink back to the bottle.
If frozen, the ink is still good to use after being put back to the room temperature.
Yidege brand ink can be storage for years even after opened. The only issue of opened ink (after years) is turning to thicker. Just diluted by clear water and use a brush to even the ink and water.  
For the better result of dilution, mixing thicker ink and water in an ink stone, then grounding by an ink for stick for couple minutes.