How to Appraise an Heirloom

That's a really good question. I was updating some insurance information when I realized I did not have the grandfather clock listed in with my posessions. This clock was actually made by my Grandfather, William Harris Jackson. He finished the clock in 1979. He had been a welder for Container Corp. of America and when he retired he took up woodworking. I can remember being in awe of the clock when he gave it to my mother. I was a teenager at the time and marveled at the fact that MY grandfather made that! He has since passed on and now I display it proudly in my living room. I know that the kit he purchased was $200 in 1977 or '78. The time piece was another $100 dollars and he paid someone to install the glass panes. How can you put a price on someones labor of love? He made it as a gift. Can you put yourself in his mindset while he was crafting this? I'm sure he was thinking "I have to make this just right". I believe that I would have to personally appraise this clock at priceless.