Continuing with the Jewel Sutta.
3. “Whatever treasure there be either here or in the world beyond, whatever precious jewel there be in the heavenly worlds, there is nought comparable to the Tathagata (the perfect One). This precious jewel is the Buddha. By this (asseveration of the) truth may there be happiness.
The 3rd verse is a proclamation. The power and impact of this proclamation is based on the ultimate truth. It leaves no room for doubt.
The appearance of a Buddha such as Sakyamuni Buddha, brings happiness to all beings because he taught a way towards Ultimate Happiness (Enlightenment). In Buddhism, Buddha is not a unique being. It is not an unfathomable state reserved for a single being. Enlightenment is an attainable Truth. Everyone can become a Buddha. Therefore it is precious.
Although the ultimate truth is attainable by all; only a few are determined enough to attain it. Therefore Buddha rarely appears in the world.
In the long timeline of world existence, a supreme Buddha such as Sakyamuni Buddha; only appears for a short period of about 80 years. In Buddhist scriptures, we talk about world creations that happened over millions of years.Evolutions of beings that happened over millions of years. Maturity of human civilisations that happened over thousands of years etc. All this adds up to form an extensive long period of time. A supreme Buddha like Sakyamuni only appears for 80 years. Therefore the appearance of Buddha is rare and very precious.
The numbers of sentient beings are mind boggling. Of these limitless numbers of beings in existence in the 3 periods of time (past, present and future), the appearance of a supreme Buddha like Sakyamuni is super rare.(as discussed above) Therefore, a Buddha is rare.
A supreme Buddha appears only when all Buddha dharma had been forgotten. The supreme Buddha attained the ultimate Truth on his own effort. Then he must have the ability to formulate a method to teach others. His career of teaching will cause the existence of Buddha Dharma in Samsara. Like all things else in Samsara, the Buddha dharma that we know of, is also impermanent. It will ultimately cease to exist too.
Not all beings have the opportunity to meet the Buddha directly,when He is physically in Samsara.
Not all beings have the opportunity to know about Buddha. This includes the period of time when Buddha Dharma has not been forgotten and lost yet. (for example,now)
If you are reading this, then congrats, we are one of the fortunate few who heard about Buddha.
This precious jewel is the Buddha.By this (asseveration of the) truth may there be happiness.
“Ratana Sutta: The Jewel Discourse” (Sn 2.1), translated from the Pali by Piyadassi Thera. Access to Insight (BCBS Edition), 30 November 2013, http://www.accesstoinsight.org/tipitaka/kn/snp/snp.2.01.piya.html .