Pour 1 cup water into a medium bowl, sprinkle gelatin on top and set aside to soften for 5 minutes. Microwave gelatin at full power for 2 minutes and then stir to dissolve. Whisk in sugar and lemon juice; whisk in pear nectar and set aside.
Peel and quarter 1 pear. Cut lengthwise in slices and arrange in a 6-cup gelatin ring mold. Pour in half of gelatin mixture and then refrigerate until set, about 45 minutes. Repeat with remaining pear and gelatin mixture, layering on top of jelled gelatin; refrigerate.
To unmold gelatin: Dip chilled mold in 2 inches of hot water for about 15 seconds. Next, place a serving platter on top of mold and invert. Then remove mold. Cut gelatin into slices and serve each slice with a drizzle of yogurt.