1. Prepare the cucumbers: Peel the two large cucumbers and roughly chop them into 1-2 inch pieces. This helps ensure a smoother texture and brighter green color.

2. Blend the cucumber: Place the chopped cucumbers into a high-speed blender. Add about 1 cup of the cold water to aid in blending. Blend on high until the cucumber is completely smooth and no large chunks remain, creating a vibrant green liquid.

3. Strain the cucumber juice: Set a fine-mesh sieve over a large pitcher or bowl. Pour the blended cucumber mixture through the sieve. Use the back of a spoon or a spatula to press down on the solids, extracting as much liquid as possible. Discard the pulp.

4. Combine with lemon juice and sugar: To the strained cucumber juice in the pitcher, add the fresh lemon juice and the granulated sugar. Stir well until the sugar is completely dissolved. Taste and adjust sweetness as desired.

5. Add remaining water and chill: Pour in the remaining 3 cups of cold water and stir again to combine thoroughly. Taste one final time to ensure balanced flavors.

6. Serve and garnish: Fill glasses with plenty of ice. Pour the cucumber lemonade over the ice. For presentation, garnish each glass with a thin lemon slice and a delicate cucumber ribbon (made by shaving thin strips from a fresh cucumber with a vegetable peeler). Serve immediately and enjoy!